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    Structural analysis: from method andmetaphor to theory and substanceBarry Wellman

    Structural (or network) analysis has mystified many social scientists. Somehave rejected it as mere m ethodology, which lacks due rega rd fo r sub stantiv eissues. Some have fled from its unusual terms and techniques, not havingplayed with blocks a n d gra ph s since gr am m ar school. Some have dismissedone portion for the who le, saying, for exam ple, th at their study of classstructure has little need for the focus on friendship ties emphasized innetwork analysis. And some have scorned it as nothing new, claiming thatthey also study "social structure." O the rs have bolted o n variables such asnetwork "density" as they w ould a turbocharge r in ord er t o boost explainedvariance. Still others, attracted by the capability of studying nonhierar-chical, nong roup struc tures, have expand ed structural analys is in to a netw orkideology tha t advocates egalitarian, op en com mu nities. Som e have even used"network" as a verb an d "networking" as a no un to advo cate the deliberatecreation an d use of social ne tw or ks for such desired e nds a s getting jobs o rintegrating communities.

    These misconceptions have arisen because too many analysts and

    This chapter was prepared with the significant assistance of members of the StructuralAnalysis Program me, University of T or on to . 5. D. Berkowitz. Ro bert Brym, Ju ne C orm an,Bonnie Er~ckson,Harrie t Friedmann, Leslie H ow ard , Nancy Howell, R. J. Richardson, L orneTepperman, and Jack Wayne contributed ideas and commented on drafts. I have benefited aswell from discussion w ith H . Russell Bernard, Jerom e Bruner, Rona ld Burt, Douglas Cau lkins,Ivan Chase, Patrick Doreian, Linton Freem an, Beatrice d e Gelder, H an s J. Hummell, JudithKjellburg, Edward Laumann, J . Clyde Mitchell, Robert Mokken, Carolyn Mullins, LeslieSalzinger, Emanuel Schegloff, Neil Smelser, Albert Som it, Charles T illy, Beverly Wellman an dHarrison White.Support for this wor k ha s been provided by the Social Sciences and Hum anities R esearchCouncil of Canada; the National Welfare Grants Directorate of Health and Welfare Canada; theCenter for Studies of M etropolitan Problems (U.S. Natio nal lnstitute of M ental He alth); theNetherlands [n st ~ tu te or Advanced Studies; the Institute for U rban and Regional D evelop-ment, University of California; and the Structural Analysis Programme and Centre forUrban and Community Studies, University of Toronto. Although I have benefited greatlyfrom all this assistance and discussion, 1 take sole responsibility for the result.

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    ro Barry Wellmanpracti t ioners have (m is)used "structural analysis" as a mixed ba g of term san d techniques. S ome have hardened i t in to a method, whereas oth ers havesoftened i t in to a metaphor. Many have l imited the power of the approachby treating all units a s if they h ad the sam e resources, all ties as if they weresymmetrical , and the contents of all t ies as if they were equivalent.Yet, structural analysis does not derive i ts power from the partialapplication of this concept or that measure. It is a comprehensive paradig-m atic way of taking social s truc ture seriously by studying directly h owpa tte rn s of ties alloc ate resources in a social system. Th us , i ts strength lies inits integrated application of theoretical concepts, ways of collecting andanalyzing data , and a growing, cumulat ing body of su bsta ntiv e findings.

    Until recently, structural analysis has had neither a basic programmaticstatement nor a s tandard text . Instead, i t has tended to accumulate part ia lprinciples an d conclusions from emp irical s tudies and oral lore. Th er e havebeen three dist inct research tradit ions, an d mo st ad her en ts of each tradit ionhave not ass imi la ted the wo rk of the o ther two . Hence , ra ther tha n ad opt o nestandard model, structural analysts have used a number of different modelswith shared family resemblances. Now, much work is coalescing, andresearchers are forming gro ups , s tart ing their ow n journals , an d publ ishingwidely in mainstream books and journals. 'In the course of t ime, s truc tura l analysis has emerged as a dist inctive fo rmof social inquiry having five paradigmatic characterist ics that provide i tsunder lying intellectual unity:

    I . Behavior is interpreted in term s of s truc tura l con stra ints on activity,rath er th an in term s of inne r forces within units (e.g. , "socializationto norms") that impel behavior in a voluntarist ic, sometim esteleological, push toward a desired goal.t. Analyses focus on the relations between units, instead of trying toso rt units into categories defined by the inne r a ttrib ute s (o r essences)of these units.

    j. A central considerat ion is how the pat terned relat ionships amongmultiple alters jointly affect network members' behavior. Hence, itis no t assumed tha t network mem bers engage only in mult iple duetswith separate alters.

    4. Structure is treated as a network of network s that may o r may n ot beparti t ioned into discrete groups. It is not assumed a priori thatt ightly bo unded gro up s are, intrinsically, the building b locks of thestructure.

    5 . Analytic method s deal directly with the patterned, relational na tureof social s t ructure in order to supplement - and somet imes sup-plant - mainstream stat is t ical methods that demand independentunits of analysis.

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    Structura l analys is : from m eta ph or to subs tance 21My objective in this chapter is to describe this structural analyticparadigm: its development, distinguishing characteristics, and analyticprinciples. N o t all structu ral ana lysts will agree with my desc ription. Indeed,some wou ld no t even call themselves "structural analysts." Neve rtheless, Ibelieve that I am able to show a fundamental uni ty under lying the manystudies that I discuss.

    Research traditionsT h e (mostly Bri tish) anthropolog ical de velopm ent of thesocia l ne tw ork concept

    The concern of s tructural analysts with the direct s tudy of networks ofconcrete social relat ions conne cts s trongly back to post-World W a r I1developments in British social anth ropo logy . ' T h en as no w , anth ropo logistspaid a good deal of at tent ion to cul tural systems of normative r ights andduties that prescribe prop er behavior w ithin such bo un ded g ro up s as t ribes,villages, an d w o rk units. A lthou gh British "structu ral-func tionalists" ha dused network metaphors as partial, allusive descriptions of social structure(e.g., Radcliffe-Brow n, 1940; see also Sun dt, 1857; Bo han nan , 195 4), theirresearch had focused on how cultures prescr ibe proper behavior withinbounded g rou ps (Boissevain, 1979). N o t only were su ch cultural systemssimpler to descr ibe than the great var iety of actual behavior , but thestructural-funct ionalis ts believed th at in focusing o n c ulture they werereducing behavioral noise and thus ge tting a t the essence of social systems.

    W hatever the meri ts of such norm ative analyses when ap plied to bound edgroups, they have difficulty in dea ling w ith social systems in wh ich ties cutacross " the fram ew ork of boun de d inst i tut ionalized gro up s o r categories" incomplex ways (Barnes, 1969: 72). T o study these crosscutt ing t ies, severalanthropologis ts in the 1950s shif ted at tent ion away from cultural systemstoward s t ruc tura l systems of concrete ties an d network s (e.g ., Nadel , ~ 9 5 7 ;Barnes, 1971) and began developing social netw ork conce pts mo re systema t-ically an d self-consciously. Th es e analysts defined a ne tw ork a s a set of tieslinking social system m em bers acro ss social categories and bou nded groups .Some anth rop olo gis ts especial ly felt the need for netw ork analyt ic toolsafter W orld W a r 11 wh en they began study ing large strea m s of m igran tsleaving culturally homogeneous villages and tribes for polyglot cit ies andindustrial areas. They feared that these migrants, in leaving behind thenormative guidance of their homelands, would become isolated anddisorganized in "mass societ ies." Ad minis trators w orr ie d that these newurbani tes wou ld be prone to s ink in to apathe t ic despai r or to s t r ike out inuns t ructured, mindless mobs ( these views are summ arized in Ko rnhau ser ,

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    Structural analysis: from metaphor to substance 231955, 1971), many American sociologists became acquainted with his earlytwentieth-century a rgum ent t h ~he forms of social relations greatlydetermine their contents . They dr ew from his w ork an interest in ho w the s izeof social systems and the ways in which relationships are interconnectedconstrain individual behavior and dyadic exchange. T o som e, such astructural emphasis was a welcome challenge to the more psychologistic,needs-driven analyses advocated by the dominant American sociologicalbrand of structural-functionalism (e.g., Parsons, 1951, 1960).

    As knowledge of the British anthropologists' work diffused across theAtlantic, it intersected with, reinforced, and modified American sociologicalinterest in structural analysis. The scope of inquiries expanded, as Britishempiricism fit well with the American penchant for quantitative measure-ment and statistical analysis.

    American interest in s tructural form st imulated effor ts to map interper-sonal relations and to develop fine-grained methods for describing theirpatterns. "Sociometrists" started using netw ork diag ram s to representinterpersonal relations in small grou ps (e.g., Co lem an, 1961; for a p recurso r,see M oren o, 1934). Subsequently, ep idemiologists an d inform ation scientistsbegan conceiving of the diffusion of disease, information, and sundry otherthings as a social netw ork phe nom enon (Co lem an, Katz, and M anzel , 1966;Rapo port , 1979; Roge rs and Kincaid, 1981).

    Struc tural analysts then began using the vocabulary of rud ime ntary "graphtheory" - he f ield of m athema tics devoted to s tudying the arrangem ent ofpoints and lines - o describe l inkages am on g the me mb ers of social systemsand to manipulate these representat ions in order to probe the underlying"deep s tructures" connec t ing and cleaving social systems (H ara ry , No rm an,and Cartwright , 1965; Frank, 1981). Yet point-and-l ine diagrams areclut tered when used to s tudy networks wi th more than about a dozenmembers ; M cCa nn an d White's (Cha pter 14) graphic depiction of thecitation n etw ork of oxygen chem ists in th e 1780s is at abo ut th e ou ter l imits oflegibility (see Figure 2.1, wh ich is based o n Figure 14.6). Con seque ntlyanalysts have co m e to use matr ices t o s tudy social ne two rks (Figure 2 .2 ) . T h euse of m atrices ha s ma de it possible to stud y man y m ore m em bers of socialsystems and many more types of t ies, and it has fit well with the use ofco m pu ters t o reveal such underlying stru ctu ral features as cliques, centralmem bers , and indirect l inkages.

    T he research gro up aro un d Harr ison W hite a t Harv ard in the 1960s and1970s played an especially important role in these efforts. White wrote keypro gr am m atic pape rs (e.g., 1965,1966) claiming all of sociologistic sociologyfor s tructu ral analysis . H e also performed a variety of exem plary analyses(e.g., 197oa) an d trained m ore t ha n a score of gra du ate studen ts in his lectures(unfortunately, unpublished) and seminars. In the words of one influentialpaper, "The presently existing, largely categorical descriptions of social

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    FROM-aume

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    ParmentierPelletierPriestleyProustSageVandermondeWoulfe

    Structural analysis: from metaphor to substance 251 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 2 3 24 25 26 2 7 28 29 30 31

    X

    X X X

    Figure 2.2. M at ri x repr esenta tion of F igure 2.1. Presence of t ierepresented by X; absence of t ie represented by blank. [Note: Computers torage would be binary (I / o) or as a vector (e.g ., Black-03 :r7) . ]

    s t ruc ture have no so l id theore t i ca l g rounding; fur the rmore , ne twork con-cepts may provide the only way to cons t ruct a theory of socia l s t ruc ture"(W hite , Bo orm an, a nd Breiger, 1976: 732 ) .

    American s t ruc tura l analys ts have had two dis t inc t sens ibi l i t ies . Aninfluential minority are formalists (e.g. , Lorrain and White, 1971; Fararo,1973; also see many of the papers in H o l l a nd a nd Le i nha rd t , 1979) .Con cent ra t ing o n the form of ne twork pa t t e rns ra the r than the i r conten t ,they hav e share d a Simm elian sensibil i ty tha t s im ilar pat terns of ties may hav es imi la r behavioral consequences , no mat te r wha t the subs tan t ive contex t .Pushed to i t s ext reme, thei r a rgument has been tha t the pat tern ofrelat ionships is substantial ly the same as the content .

    T h e second sens ibi li ty , m ore widely represented in this book , h as been a

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    26 Barry Wellmanbroad strtrcturalism, using a variety of network analytic concepts andtechniques to address the substantive questions that have preoccupied mostsociologists. Structural analysts with this sensibility have approached thesequestions from two routes. Many view networks much as astronomers viewthe universe: as outside observers studying relationships linking all membersof a population. The resulting whole network studies describe the compre-hensive structure of role relationships in a social system. Through manipulat-ing matrices, analysts can find patterns of connectivity and cleavage withinsocial systems, "structurally equivalent" role relationships among systemmembers, changes in network structures over time, and the ways in whichsystem members are directly and indirectly connected.A basic strength of the whole network approach is that it permits

    simultaneous views of the social system as a whole and of the parts that makeup the system. Analysts are therefore able to trace lateral and vertical flows ofinformation, identify sources and targets, and detect structural constraintsoperating on flows of resources. Whole network analysts either study thesystem for its own sake asking, for example, if it is socially integrated or ifthere is a ruling class or they analyze how the structure of a system affects thebehavior and attitude of its members. They ask, for example, if sparsely knitnetworks lead to sensed social isolation or if persons with ties to two networkclusters behave differently from those whose ties are wholly bound upwithin one cluster (e.g., Kapferer, 1972; Bernard and Killworth, 1973).

    Some of the most interesting whole network studies have used member-ships on boards of directors to describe relationships between largecorporations. Here the nodes of the networks are the large corporationsthemselves, and the membership of a corporate executive on anothercorporation's board is used as a trace of a tie between the two corporations."Such work has powerful implications even in its descriptive form: Itgraphically portrays the overall connectivity of dominant corporations andthe presence of interest-group alliances among them. Moreover, the work haspredictive power: For example, sectors of the Canadian economy in whichthe corporations are heavily interconnected tend to have high rates of profit(Carrington, 1981).

    Whole network studies are not always methodologically feasible oranalytically appropriate. Those who use them find that they must define theboundaries of a population, compile a list of all the members of thispopulation, collect a list of all the direct ties (of the sort the analyst isinterested in) between the members of this population, and employ a varietyof statistical and mathematical techniques to tease out some underlyingstructural properties of the social systems. Yet, with the current limitations ofcomputer hardware and software, analysts have been able to study only a fewtypes of relationships in populations no larger than several hundred.Moreover, it is not feasible to obtain complete lists of population members

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    Structural analysis: from m eta ph or t o substance

    NEIGHBORS

    FRIENDS CO-WORKERS

    Figure 2.3. Typical personal network of a n East Yorker. (See Wellman,Carrington, and Hall, Chapter 6.)and their ties in ma ny large, naturally occu rring settings. Indeed, att em pts toimpose improper boundaries may often lead to analytic confusion, as wascommon before 1970 when urban socio logis ts ignored nonneighborhoodfriendships a nd wrongly decla red urba nites t o be isolated an d lonely (see thereview in Wellman and Leighton, 1979).

    Because of such l im itat ions, many s tructural analysts have concentrated o nstudying smaller egocentric (o r personal) n etw orks - defined from thestandpoint of focal individuals. There are positive reasons as well fors tudying egocentr ic networks. Rather than showing the universe as i t isperceived by an outs ide observe r, they pro vide Ptolem aic views of net w ork sas they may be perceived by the individuals at their centers.

    Figure 2.3, for exam ple, sh ow s the significant interpe rsona l ties of a typicalNo rth A merican. She is direct ly t ied w ith each ne two rk m embe r (bydefinition), and she perceives many network members as being linked witheach oth er. (F or the sak e of clarity, Figure 2.3 o m its the direct ties betweenfocal-person and network members . ) She is aware of a densely knit corecluster of kin - hree of w hom she sees as her intimates - nd m ore sparsely knitrelations among half a dozen friends and neighbors. In her eyes, only her

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    28 Barry Wellmanon e work mate stands a pa rt , the wo rk mate's isolation reflecting both thefocal person's separation of employed and social life, and her use ofinterperso nal t ies to deal with domestic concerns an d not prob lem s of earn inga l iving (see W ellman, 1985; W ellma n, Carrington , a nd Hall , C ha pte r 6, fo rmo re detai ls).Egocentric network studies have often meshed well with tradit ionalAmerlcan survey techniques. Researchers have typically interviewed a (oftenlarge) sample of respondents, inquiring about the composit ion, relationalpatterns, and contents of "their" netw orks.

    As in the many studies of urban "personal communities," such analyseshave demonstrated the cont inued ab und anc e an d vital ity of primary relat ionsin social systems transfo rm ed by capitalism, urban ization, industrialization ,bureaucrat izat ion, and technology. T hese egocentric network studies havedocumented the pervasiveness and importance of connectivity, therebyrebutting mass society co ntentions tha t recent large-scale social transform a-t ions have produced isolat ion and al ienat ion. Numerous scholars havedescribed how netw orks l ink individuals throug h st ron g and w eak ties, s i tua tethem in larger social systems, and affect the flows of resources to and fromthem.

    Questions of resource access are closely associated with questions ofne twork form. Ho w does one obtain material goods , emot ional support , o rinformat ion f rom other ne two rk mem bers? A nu m ber of s tud ies havedemonstrated the effects of different network patterns of access to suchdiverse resources as lobs, scientific information, abortionists, and emotionalsupp ort . Investigators have paid a great deal of at tention to "social supp ort ,"and many studies have suggested that the characterist ics of their networksmay significantly affect focal individuals' health, longevity, and well-being.'

    In recent years, analy sts of bo th whole an d egocentric netw orks have beenconcerned with the effects of ne tw ork prop erties on the integr ation of large-scale social systems, a sociological preoc cupa tion since Emile D urkh eim . Inparticular, they have studied:

    0 the cond itions under w hich triad s of t ies conc atenate to for m largernetw orks (Davis an d Leinhard t, 1972; Davis, 1979; H olla nd an dLeinhardt, 1977)

    0 the addi t ion of new members to networks through ramifying t ies(Rapoport , 1979)

    0 th e likelihood of ne twor k t ies between m em bers of large-scale socialsystems (M ilgram , 1967: W hite, 1970b; Bernard an d Killworth,1978; Pool and Kochen, 1978)

    the impact of interpersonal network characterist ics on the in-tegr ation of large-scale social systems (Gr ano vette r, 1973, 1982;Laumann, 1973; Brieger, Chapter 4).

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    30 Barry WellmanA second set of scholars has used structural analytic concepts, but not

    usually network methods, to study dependency links in systems of nation-states and among other macrostructural interest groups. Their work began inreaction to the prevailing scholarly view of the 1950s and 196os, whichattributed the underdevelopment of Third World states primarily to a state'sinternally "backward" social structure, nornis, and values (e.g., McClelland,1961; Hagen, 1962; Pye, 1962; Moore, 1979). These structural analysts havegone on to demonstrate that asymmetric relations of trade and powerbetween states, regions, and interest groups have affected the course of ThirdWorld development much more than internal backwardness.

    This "political economic" approach has adherents throughout the world,especially in Canada, which has been extensively involved in inter-national, interregional and intergroup dependency networks (Richardson andWellman, 1985). A number of research groups with varying interests havecontributed to this work: For example, "dependency" and "world-systemsvanalysts have studied how international terms of trade affect the internalstructures of dependent countries (Frank, 1969; Wallerstein, 1974; Friedmannand Wayne, 1977; Friedmann, 1978, 1980,1982, Chapter 11; Skocpol, 1979;Wayne, 1980; Delacroix and Ragin, 1981).

    This work has led other structural analysts to consider more fully howpower over access to resources affects relationships and to examine linkagesbetween large-scale units as well as between persons. The reciprocal effecthas been weaker. Whether through ignorance or distaste for quantitativereasoning, few "political economists" have used structural analytic tools toexamine relationships between states and interest groups (see Berkowitz,Chapter to; Friedmann, Chapter 11; Tilly, Chapter 12;White, Chapter 9).Yet the structural analytic approach shows particular promise for Marxian-informed studies of how power-dependency networks are associated withmodes of production, consistent with Marx's injunction that class relation-ships be analyzed in structural rather than categorical terms (Godelier, 1978;lnsurgent Sociologist, 1979).

    The structural alternativeStructural analysis is more than a set of topics or a bag of methodologicaltricks with a new mystifying vocabulary. It is a distinctive way of tacklingsociological questions that provides a means to the end of taking socialstructure seriously. In this section I present five general principles thattogether substantially guide structural analytic work in a wide variety ofsubstantive areas.

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    Structural analysis: from metaphor to substance 3 1Structured social relationships are a m ore pow erful source ofsociological explanation than personal attributes of systemmembers

    Many mainstream sociological studies treat social structure and process asthe sum of individual actors ' personal a t tr ibutes. T hes e at tr ibutes, w hetherderived genetically (e.g., age, ge nd er) or socially (e.g., socioe cono m ic st atu s,political attitudes), are treated as entities that individuals possess asindividuals. Each is treated as a n in dep end ent unit of analysis an d lum ped i ntosocial categories with oth ers possessing sim ilar attri bu te profiles. T h e me thodof analy sis - be i t cross-tabulat ion, correlat ion, or m ore complex m ult ivariatetechniques - proceeds by sorting individuals possessing similar combina-t ions of a t tr ibutes into similar analytic cells , for example, old women ofhigh socioeconomic status who vote Republican.

    Such taxonomic analyses group individuals into similar-at tr ibutecategories w ithou t re gard fo r the struc tur e of relationships in which suchindividuals are embedded - both internally within groups and externallybetween groups. Fo r exam ple, " there has been a tendency t o examine thecapital is t c lass and the peti t bourgeoisie as dist inct pheno me na rather th an asclass analysis should de m and , in relation t o one another" (Clem ent, 1983:viii). Such analyses inevitably conclude t h at social behavior is the result of th efact that individuals possess common attr ibutes rather than that they areinvolved in structured social relationships. Hence, although most main-stream sociologists profess to be studying social s tructure through at tr i-butional analyses, their inheren t "methodo logical individualism" leads themto neglect social s tructure and th e relat ions am on g individuals (Colem an,1958:r8). Their so-called structural techniques examine relat ionshipsbetween variables - no t social system mem bers. Such analyses, interre latingthe personal attribute s of discrete individuals, lead t o a variety of prob lem s.

    I . Attribute analyses treat each social system member as an astructuralindependent unit. Since analyses of this kind m ust assum e ra nd om linkages,they cann ot take in to account members ' pat terned connections (B erkowitz ,Chapter 18). "But of course individuals d o not ac t random ly with respect toone another. The y form a t tachm ents to cer tain persons , they grou p togetherin cliques, they establish institutions" (C ole m an , 1964: 88). Hence, aggregat-ing each member 's characteris t ics independently obscures or destroysstructural information in the same way that centr ifuging genes destroyss t ruc ture whi le provid ing informat ion abou t com posi t ion .

    2 . Such analyses concentrate on the at tr ibutes that discrete individualspossess. For example, they treat an inherently structural phenomenon,"social class," as a person al att rib ut e, "socioecono mic status." Yet "it is asuseful t o tell me th at 'p ow er' is localized in th e X club of N ew Yo rk a s it is t o

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    32 Barry Wellmantell me th a t my sou l resides in my pineal gla nd ; the prem ise is false . . . socialvitalism" (Levine an d Roy , 1979:360-1).

    3. Many analyses compare dis tr ibut ions and correlat ions of aggregatedcategories of at t r ibutes . They focus o n the causes a n d correlates of internalvariat ion w ithin a social category, for exam ple, relat ing socioeconom ic s tatu sto voting behavior. At best, such analyses use categorical memberships asproxy measures of s tructured relationships (Friedman n, 1979;Breiger, 1981).

    4. When analysts consider a category to be truly relevant rather than aproxy, they expect members of that category to behave in s imilar ways.Ho wev er , coordinat ing ties am on g category mem bers may be responsible fo rthe s imilar behav ior . H o w these t ies com e to exis t and function is s ti ll open toquest ion. Thu s, the a r t isans of the V endee did not al l rise up spon taneously asthe aggregated indig nation of tho usa nd s of individuals. Ra ther, t ies betweenlocal communit ies and occupational groups s tructured poli t ical act ivi ty(Tilly, 1967).

    5. If analysts treat only categories an d grou ps as relevant organ ization alunits, this affects the ways in which they analyze ties th a t cut across categoryand gr ou p boun daries . They mu st t reat such t ies as marginal , when in fact thecategory o r gr ou p may be t ruly ir relevant to th e funct ioning of t ies(Berkowitz, Chapter 18). For exam ple, terming migrants "marginal" maywell ignore their concrete urban relationships, while unduly positingattachments back to ancestral villages.

    6 . Aggregat ing individuals ' at t r ibutes encourages analysts to interpretsocial behavior as a normatively guided phenomenon. The aggregat ionprocess has destroyed information about s tructural l inkages but retainedinformation about internal ized norms. Analysts seize upon these norms toexplain social behavior (Erickson, Chapter 5).

    7. Normative interpretat ions lead analysts to look for behavior that isprescr ibed or common among category members . They e i ther do notrecognize o ther k inds of behavior o r label i t as deviant. Yet i t may be dev iantonly beca use an aly sts persist in misidentifying it with a categorical referencegroup.6

    The se observations lead s t ructura l analysts to wonder if "the stuff of socialaction is, in fact, w aiting t o be discovered in the ne tw ork of interstices tha texis t outs ide the norm at ive cons t ructs and the a t t r ibute breakd ow ns of o ureveryday categories." T o find out, analysts "must aggregate (social)regularit ies in a fashion consistent with their inherent nature asnetworks" - hat is , they must group individuals by equivalent structurallocat ion rather than equivalent categorical m emberships (W hite, Boorm an,and Breiger, 1976: 734).

    People belong to networks as well as to categories . Structural analystsbelieve th at categorical m embe rships reflect underlying s tru ctu ral relation-ships, th at is, pattern ed differences in the kind s of resources with which they

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    Structural analysis: from metaphor to substance 33are linked. They d o not treat social class, for e xam ple, as a set of statusesoccupied by mem bers of a popu lation, bu t as a su m m ary label for eco nom icrelations of power and dependency (Wright, 1977, 1980).

    This shift in perspective markedly affects analysis: Once weassume that the unit of analysis is . . . a "world system" an d notthe "state" o r the "nation" o r the "people" . . we shif t from aconcern with the attributive characteristics of states to concernwith relational characteristics of states. We shift from seeingclasses (an d status-groups) as gro up s w ithin a s ta te t o seeingthem as grou ps w ithin a wo rld-ec ono m y. (W allerstein, 1976: xi)Norms emerge from location in structured systems of socialrelationships

    Although many m ainstream sociologists d o use the structu ral loc ation ofpersons to explain their acqu isition of no rm s an d values, they still tre atpersons as individuals acting in response t o their internalized norm s. Th eyfind purportedly sociological regularities when persons who have similarpersonal attributes behave similarly in response to shared norms. Suchexplanations, concerned as they are with aggregated sets of individualmotives for action, are ultimately psychological and not sociological incharacter, as they neglect the ways in which va riati on s in struc ture d access t oscarce resources deter m ine opp ortun ities an d con straints for behavior. T he seexplanations - with their s tro ng echoes of Durk heim 's views (e.g.,1893) - mplicitly treat social integra tion as the no rm al state . T he y define therelationship of person s t o social system s "in term s of shared con sciousn ess,commitments, normative orientations, values, systems of explanation"(H ow ard, 1974: 5 ) .

    In co ntr ast, struc tura l analysts first seek exp lan atio ns in th e regularities ofhow people a nd collectivities actually behave r ath er th an in th e regularities oftheir beliefs about how they ought to behave. They interpret behavior interms of structural constraints on activity instead of assuming that innerforces (i.e., internalized norms) impel actors in voluntaristic, sometimesteleological, behavior t ow ard desired goals. T hu s, they trea t nor m s as effectsof structural location, not causes (see Erickson, Chapter 5 ) .

    Structural analysts contend th at acco untin g for individual motives is a jobbetter left to psychologists. They suggest that sociologists should explainbehavior by analyzing the social distribution of possibilities: the unequalavailability of resources - such as information, wea lth, an d influence - a n dthe structures throu gh which people may gain access t o them. Th ey stu dy theprocesses through which resources are garnered or mobilized - uch asexchange, dependency, co mp eti t ion, an d coali t ion - and the social systemsthat develop ou t of these processes (W hite , Ch apter 9) .

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    I34 Barry Wellman I1 If norms are to be treated as effects, then how can analysts explain why Ipeople behave the way they do ? Structural analysts deal with norm ative 1motivat ion in four ways:1 I . Some analysts exclude quest ions of h um an motivat ion a nd conc entrate 1on describing and explaining social systems only in systemic terms (e.g., 1~ o o r m a nnd Levitt , 1980; Levine and Spada ro, Ch apter 17). O n e s tudy, forexample, modeled systems of social mobility in the American Episcopalc h u rc h (Whi te . 197oa; Stewman and K onda, 1 9 8 d I t found the Episcopal 1ministers ' motives for changing posi t ions to be ir relevant to their regularm ove m ents throug h linked "vacancy chains." An other set of studies ha s /

    m ap pe d a variety of re lat ions am ong ma jor Canadian corporat ions , show ing 1l inks to the s ta te , cont inui ty in in tercorporate cont rol over t ime, andassociations between densely kn it cor po rate relations in business sectors and 1I high rates of profit (e g . , i lerkow itr , 1980, Ch apte r 10; Ca rr ing ton, 1981; 11 Niosi, 1981; Corman, 1983).

    2. M any analysts concen trate o n analyzing rhe structural determ inan ts of 11 hum an f reedom and behavior . They d o not deny the exis tence an d force of

    norms, but assum e that no rms operate only within the cons t ra in ts an dI oppo rtunit ies social s t ructures provide for hu m an behavior . As W hite argues:I M y pe rs ona l values are voluntar is t ic individualism. 1 wish formyself, an d others, a s much freedom a s possible, i.e., as muc hdignity as possible. T hi s value becomes a mockery w itho ut

    facing the constraints of social structure. Much better a twig ofgenuine freedom wrung from a t ree of constraint than an

    I artificial tinsel forest of freedom.. . .Most sociology and social science, especially in the U.S., takesthe uiew of voluntaristic individualism: basic reality is inindividuals ' values and choices, social structure being derivedtherefrom, being merely epiphenomena]. . The fruit of muchsociology theory is this deception: social structure must be thesu m of individual values so you can define it a priori ou t ofyou r head . O r in recent versions, you can find it by poo lingresponses of pop ulation s of que stionn aires. (Wh ite, 1968)

    j. Some analysts have placed s tructural and n orma tive explanat ions h ead /to head, arguing that s t ructural con straints an d oppo rtunit ies explain socialbehavior m ore fully that norm ative mo tivat ion: "Most s tudies find l i tt le or n ocorrela tion between an individual's att i tud es o r norm ative beliefs an d hisbeha vior" (Ca nc ian , 1975: 112; see also De utscher, 1973). In on e ex pe rim en t,ma ny pe rsons obeyed orde rs to shock s trangers and kin " lethally": II

    I [M an y we re] agains t wh at they did t o the learner, a nd many 1protested even while they obeyed. But between thoughts, words, 11 and the--rit ical step of disobeying a malevolent authority, l ies-- - -- - -

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    Structural analysis: from m eta ph or t o substance 35another ingredient, the capacity for transforming beliefs andvalues into action. Some subjects were totally convinced of thewrongness of wha t they were doing but could n ot br ingthemselves to m ake an open break wi th author i ty . Som e derivedsatisfaction from their thoughts and felt that - within themselves,at least - th ey had been on th e s ide of the angels. W ha t theyfailed to realize is that subjective feelings are largely irrelevant tothe moral issue at hand so long as they are t ransformed intoact ion. (Milgram, I 974: 10)

    The re is a clear co ntra st between norm ative a nd s tructural s tudies of"modernization." No rma tive s tudies , o n the on e ha nd , argu e tha t ruralThird World inhabitants go through an a t t i tudinal chan ge of "becomingmodern" before they participate in urban industrial social systems (Inkelesand Smith, 1974). Structural s tudies , on the oth er ha nd, argue tha t ruralvillagers do not migrate to an industrial city because of newly adoptedmodern norms an d values, but because previously migrated k in, friends, an dneighbors have promised to help them find homes and jobs. Migration israrely a once-and-for-all , uprooting and isolating experience. Rather,migrants t ravel and communicate back and for th between their newresidences and ancestral homelands (Jacobson, 1973; Mitchell , 1973a;Roberts, 1973; H ow ar d, 1974; M ay er an d Ma ye r , 197 4).

    4. Some structural analysts explain the uneven dis tr ibut ion of norm s in apopulation as a sys temic phenom enon. The y a rgue that people acquirenorms, as they d o othe r pieces of inform ation, thro ug h netw ork ties. T hu sErickson an d No sanc hu k (1984) have sh ow n that the allocation of esteem a nddisesteem in the O tta w a bridge w orld has everything to d o with th e players 'behavior in bridge circles an d litt le to d o with their location in outsid e socials tructures (e.g., w ork, g ende r , age) . O n a much larger scale, argues W hite(1981, Ch ap ter g) , perceptions of co rp or atio ns are strongly affected by thekinds of structural niches they occupy in compe titive markets. T h u s, not onlyis norma tively guided beh avior structurally c on straine d, bu t the inculcationof these norm s, itself, is differentially repro duc ed throu gh netw ork structu res(see Co hen , 1969; Schild krau t, 1974; Brym, C ha pte r 13).

    Social s t ructures determ ine the o pe rat io n of d yadic relat ionshipsMany sociologists use another form of reductionist aggregation: They treatdy adic (two-p erson ) interaction as the basic relational unit of analysis (e.g.,H om an s, 1961; Backman, 1981). They look a t factors affecting the ini t iat ion,continuat ion, and loss of t ies ; the types of resources each dyad memberexchanges wi th the o ther ; and the extent to which such resources arereciprocally exchanged. They disregard structural form, making an implicitbet that they can adequately analyze ties in structural isolation, without

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    36 Barry Wellmanreference to the nature of other ties in the network or how they fit together.Thus, many studies of "social support" see interpersonal help as emergingfrom multiple duets with separate others (Hall and Wellman, 1985).

    Structural analysts point out, however, that social structural featuresgreatly determine the milieux in which dyadic ties operate. For starters, thesocial structures create relatively homogeneous "foci" within which mostindividuals choose their dyadic partners: kinship groups, cafes, workplaces,neighborhoods, and the like (Feld, 1981). As a result, "institutionallycomplete" ethnic groups -supplying a broad range of services tomembers - end to retain comparatively high proportions of their members'informal contacts (Breton, 1964).

    Once a relationship begins, its structural location continues to affect itstrongly. The pattern of ties in a social system significantly affects the flow ofresources through specific ties, so that densely knit kinship groups pull apar tspouses (Bott, 1957), and densely knit corporate relations bring high profitlevels (Carrington, 1981). Many personal community ties persist because theparticipants are embedded in social structures - kinship, work groups,friendship circles, neighboring networks -that constrain them to continue,and not because either dyad member enjoys being with the other. Indeed, theamount of reciprocity is more evenly balanced in the overall networks than itis among the specific ties within them (Wellman, Carrington, and Hall,Chapter 6).

    Structural analysts interpret all dyadic relations in the light of the twoindividuals' additional relations with other network members. "To discoverhow A , who is in touch with B and C , is affected by the relation between B andC . .. demands the use of the network concept" (Barnes, 1972: 3). Analystspoint out that dyadic relations can only be understood in the context of thestructures formed by their linkages. Sociologists cannot discover suchemergent properties as coalition formation or network density from the studyof dyads. Nor can they study structural effects, such as the positiverelationship between interlocking corporate ties and corporate profit levels(Carrington, 1981). This focus on structural form distinguishes structuralanalysis from other transactional approaches-such as "exchangetheory" - which look primarily at structural patterns as they conditiondyadic ties.'

    Even nonhuman social systems have structural properties that are morethan the sum of dyadic exchanges. Take the classic barnyard pecking order inwhich chicken A pushes chicken B away from the food, and chicken B, inturn, pushes chicken C away. Yet the overall social structure of the barnyardis not merely the aggregated sum of such dyadic dominance relationships. Attimes, chicken C may push chicken A away (i.e., a circle of dominance mayprevail rather than a linear hierarchy); at times chicken B and C may form acoalition to push chicken A away from the food. It is the multiple-way

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    Structura l analys is : f rom m etap hor to subs tance 37rela t ionships among chickens that make the barnyard pecking order acomplex structural hen omen on (Landau, 1965; Chase, 1974, 1980). Likechickens, like people. Tilly (e.g., 1975, 1978) ha s sh o w n th a t it is the link edrelat ionships of interest gro up s th at mobil ize a nd s tru ctu re poli tical act ivi ty,and not individual grievances o r s imple contes ts between tw o gro ups .

    Not only does ne tw ork s tru ctu re affect dyadic t ies , there are times wh en thelarger network i tself is the focus of at tent ion. The t ies between twoindividuals are im po rtan t not only in themselves but also as par ts of the socialnetworks in which they are embedded. Each t ie gives network membersindirect access to al l those with whom their al ters are connected. Socialsystem members use a variety of direct and indirect t ies to search forresources, often transversing several role relationships. Indirect t ies l inktogether in co m po un d rela tion ship s (e.g., "friend of a friend") tha t f itnetwork members into large social systems, t ransmit t ing and al locat ingscarce resources.

    Thus , several s t ructura l analys ts have char ted the ways in whichinformation - of ten a scarce resource - lows in s t ructura l ly pat tern ed waysthrough networks (e.g. , Lee, 5969; Richardson, Erickson, and Nosanchuk,1979; Delany, Chapter 16) . Indeed, sometimes a dyadic success may havenegative consequences a s a resul t of the dya d partners ' s t ruc tura l locat ion.For example, interpersonal networks eff icient ly t ransmit information aboutjob openings to women and subordinate minor i t ies , but the jobs to whichthey direct persons o f ten a re entra pp ing cul-de-sacs because they a re the onlysor ts o f jobs abo ut w hich ne tw ork mem bers kno w (Calzavara , 1982).

    T h e wor ld is compos ed of ne t wor ks , no t g r oupsStructura l analys ts t ry to avoid im pos ing assumpt ions a bo ut the b oundar iesof aggregates . Th ey d o not assume th at analys is can proceed on the basis of afew discrete categories - uch a s prole taria t a nd bourgeois ie or core andper iphery . They do no t as sume tha t t igh t ly bound groups a re the funda-me ntal building bloc ks of large-scale social systems - hat communi t ies , forexample , are conger ies of neighborhoods (Wel lman and Leighton, 1979) .Indeed, they cau t ion tha t descr ip t ions based o n bo unded grou ps oversimpl ifycom plex social s t ructures , t reat ing them as org an iza t ion al t rees , w he n i t is thenetw ork mem bers ' c rosscut t ing mem berships in mul t ip le socia l circles tha tweave toge ther soc ia l sys tems (a n a rgumen t da t ing back to S im mel ) .

    By s tar t ing wi th networks ra ther than wi th groups , analys ts are able tos tudy bo th t ies tha t d o no t fo rm d iscrete g roups an d n e two rks tha t a re , infact, suff iciently bou nded a n d densely knit to be terme d "groups" (Barnes,1954; Boissevain, 1974; Doreian, 1981, 1982; Seidman, 1981; Seidrnan andFoster , 1981; M cPh erson, 1982; W ilson, 1982). W h a t remain s problem atic isthe existence of ramified, spatially dispersed networks of "community ties,"

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    38 Barry Wellmaneven when they d o not fit wi thin bounded ne ighborhood o r k inshipsol idari t ies . Nonetheless, this approach provides a st ructural basis forassessing the D urkh eim ian thesis concerning the integra t ion of social systemsthrough complex divisions of labor.

    By t reating the world as a s t ructure of netw orks (an d indeed, of "n etwo rksof networks") on e is able to discover com plex hierarchies of pow er, n otmerely discrete strata (Walton, 1976; Breiger, 1979; Miller, 1980). Forexam ple, s t ructural analysis points a way o u t of the inevi tably sterile de ba teover whether external l inkages or internal c lass relat ions lead to colonialback wa rdnes s ( Fr an k, 1969; W ayne , 1975; Carrol l , 1985) by provid ing amechanism for com prehending h ow in terna l an d ex terna l rela tions in tersec twi th a nd modify each o the r (see Bodem ann, Ch apter 8) .

    St ruc tura l methods supplement and supplan tindividual ist ic m ethod s

    Because of the l inked nature of social s t ructural phenomena, s t ructuralanalysts have had to develop methods for analyzing networks of relat ion-ships among social system members. Developments have been mostprominent in the domain of quant i ta t ive analysis .

    Although statist ical methods in sociology have grown increasinglysophist icated, they cont inue to t reat individuals as independent uni ts . Thevery assum ption of s ta tis tical independence, which m akes these meth ods s oappropriate for an powerful in categorical analysis , detaches individualsfrom socia l s t ruc tures and forces ana lys t s to t rea t them as par t s of adisconnected mass. Researchers fol lowing this tack can only m easur e socialst ructure indirect ly , by organizing and summarizing numerous individualcovariations. Th ey a re forced to neglect social properties th at a re m ore t ha nthe sum of individual acts. Statist ical packages such as SPSS (Nie, Hull ,Jenland, Steinbrenner, and Bent , 1975) have become a worldview. As onereview of social indicator research has noted:

    Social structure, social process, social insti tutions - all thatwhich goes into a social scientific understanding of society -area ll near ly absent . Th e society whose condi t ions we are t o beinformed about is one of a tomist ic individuals , groupedimmutably by sex, race, and bir th cohort . Their wel l -beingcomes in discrete l i t t le packages of disconnected benefits . . . Iti s a world of work wi thout d i r ty work , where there a re unionsand strikes, but no industrial conflict . It is an economy virtuallywithout corporat ions, pol i t ics without ei ther pol i t ical part ies orpolit ical pow er. (Seidm an, 1978: 718)

    T h e sh if t away fro m methodologica l ind iv idual ism tow ard s t ruc tura l

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    Structural analysis: from metaphor to substance 39analysis calls for the development of new relational methods and theredefinition of units of analysis:

    Th e unit is (n ow ) a re la t ion , eg . , th e k inship re lat ion am ongpersons, the com m unica tion l inks am on g officers of a norganiza t ion , the f r iendship s t ruc ture wi th in a sm al l group. T h einteresting feature of a relation is its pattern: it has neither age,sex, rel igion, nor income, nor at t i tudes; a l though these may beattr ibutes of the individuals among whom the relat ion exists .These fundamental definit ions prevent s tructuralis ts fromadopting measurement techniques and methodologies availableto other sociologists (e.g., you cannot interview a friendship). Astruc tura lis t may ask w hether and to wh at degree f r iendship istransitive o r c lustered. H e may exam ine the logical consistencyof a set of kin rules, t he circularity of h iera rch y ofcomm unication, o r the cliquishness of fr iendship. We have, a syet, few tools for these tasks an d a lm ost non e up on which thereis universal agreement. Simply defining such terms as degree oftransitivity has proven difficult. (Levine an d M ullin s, 1978: 17)

    T o da te there have been th ree associated thrusts in the developm ent ofstructural methods:

    I . Popula t ions an d samples have com e to be def ined re la t ional ly ra therthan categorically.

    2. Categorical m ethod s of description an d analysis have been replacedby relational methods.

    3. Individua listic statistical techniqu es a re being used less a n d determi-na te m athemat ics m ore t o s tudy soc ia l s t ruc ture d irec tly .

    Analysts have applied stru ctu ral m eth ods in a variety of ways. Several haveused them t o tackle stat is tical problem s of analyzing social s tructu re fromsamples of egocentric networks (Granovetter, 1976; Erickson, 1978; Frank,1978; Erickson, Nosanchuk, and Lee, 1981). Some have used stochasticmodels to study search strategies, arguing that probabilistic judgments areintrinsic part s of s ocial structu res (Padg ett, 1980; Delany, C ha pt er 16).Others have developed d escriptive measures of social s tructu res based, fo rexample , o n the ir c lus ter ing in to relat ively b oun d g roup s or on the ex tent t owhich resources diffuse through them (e.g., Shepard and Arabie, 1979;Hubert, r980; White, 1980; Burt, 1980; Burt and Minor, 1982; Fienberg,Meyer , and W asserman , 1985; Erickson, C hap ter 5; M cC ann and White ,Chapter 14). Thus, researchers have been able to analyze ruling groups inAmerica by describing network clusters and social c loseness among largecorporations, s ta te authori t ies , and eli tes (e .g . , Alba and Moore, 1978;

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    40 Barry WellmanLaumann, Galaskiewicz, and Marsden, 1978; aumann and Marsden, 1979;Mintz and Schwartz, 1985).

    One noteworthy technique, "blockmodeling," inductively uncovers un-derlying role structures in a social structure by juxtaposing multipleindicators of relationships in analytic matrices. Blockmodeling thus helpsanalysts to compare actual networks with hypothesized structures (Boormanand White, 1976;White et al., 1976;Arabie, Boorman, and Levitt, 1978;Levine and Mullins, 1978;Sailer, 1978;Breiger, 1979;Light and Mullins,1979; Snyder and Kick, 1979; Carrington, Heil, and Berkowitz, 1980;Pattison, 1980; Panning, 1982; Heil 1983). Finally, some analysts usemathematical and statistical techniques to trace the course of social structureover time by modeling the interplay of relationships under specific analyticparameters (White, 197oa, b, 1981,Chapter 9; Howell, 1979, Chapter 3;Berkowitz, Chapter 18;Delany, Chapter 16).

    These specialized methods have often been the most visible manifestationsof structural analysis and may help to explain why structural analysts areoften said to be a breed apart . Yet many quantitative analysts have continuedto use standard statistical techniques in conjunction with measures ofnetwork properties (Wellman, Carrington, and Hall, Chapter 6; Howard,Chapter 7). Similarly, many analysts have continued to obtain powerfulresults from structurally informed fieldwork and archival research (Roberts,1973; omnitz, 1977; illy, 1980; alaff, 1981; odemann, Chapter 8;Brym,Chapter 13).What is distinctive about structural analysis is not the methodsused, but the particular ways in which researchers pose questions and searchfor answers.

    Some analytic principlesTh e principles in the working kits of many structural analysts are a mixtureof definitions, assumptions, partially tested hypotheses, and empiricalgeneralizations.

    I. Ties are usually asymmetrically reciprocal, differing in content andintensity.More than material goods flow through ties and networks. Flows can

    include resources such as information about one's environment and re-sources that are themselves a part of the ties - uch as gratification obtainedthrough being liked.

    Ties between two persons are usually asymmetric in the amount and kindsof resources that flow from one to the other. Few ties resemble the linkbetween Damon and Pythias - ntense, comprehensive, and symmetric. Mostare asymmetric in content and intensity. There is rarely a strict one-to-one

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    Structural analysis: from metaphor to substance 41correspondence between what two persons give to one another (Emerson,1962;Macaulay, 1963; Kadushin, 1981; C o o k , 1982; Wellman, Carr ington ,and Hall, Chapter 6; Bo d e ma n n , Ch a p te r 8).

    One study reports , for example, that only 36% of those named as closefriends and kin feel symmetrically as close to the persons who named them.The ties they define as "close" ar e with o thers. T he y often have weak er,asymmetr ic t ies to those who name them (Shulman, 1972, 1976). M a n ypersons deliberately limit their claim s for assistance fr om close ties in o rd er t omainta in the link (W ellman, Carr ington , an d Hal l , C hap ter 6). Yet suchasymmetric t ies crucially connect ne tw or k m embers t o each other, an d,through the other 's additional ties, indirectly connect them to larger socialnetworks.

    Although rarely sym metric, t ies are usually reciproc ated in a generalizedway. For example, no t only d o clients send resources to patro ns, bu t pa tro nsusually send such resources a s go ods , info rm atio n, a nd p rotection to clients.Further, the po w er of pa tr on s is partly based o n their ties with clients, as theties themselves are a scarce resource. The ties are clearly not symmetric;nevertheless they are often stable parts of a social system (Wolf, 1956;Bodemann, Chapter 8; H o w a r d , C h a p t e r 7) . Amo n g th e Ib a d a n Ha u sa inNigeria, for exam ple, reciprocal, asym metric patron-client ties m ain taincomplex trading networks over great distances (Cohen, 1969). Indeed, themost totalitarian social system s have n o t been able to function solely th rou ghone-way, coercive relat ions. R eciprocal t ies between gu ard s an d prisonerspermeate prisons and ensure compliance (Solzhenitsyn, 1968; Charr iere ,1970).

    2 . Ties l ink ne tw ork mem bers indirec tly as wel l as d i rect ly. Hence ,they m ust be def ined with in the context of la rger ne tw ork s t ruc tures .

    T he prevalence of a sym me tric ties calls into que stio n the voluntaristicassumption that t ies exist because two members of a dyad want to interactwith one another (Berscheid and Walster , 1978; Ev a n s a n d No r th wo o d ,1979).In pract ice, many t ies a re wi th ne tw ork members w ho m o ne does no tlike and with wh om one w ould n ot voluntari ly form a twosom e. Such t ies a reinvoluntary in tha t they co m e as part of the netw ork mem bership package.They may be t ies to persons who must be dea l t wi th a t work or in theneighborhood. The y may be p ar t of a so l idary k inship gr oup o r f r iendshipcircle, o r they may be patron-client ties. Desp ite their invo lun tary nature ,such t ies are often im po rta nt in terms of th e t ime spent on them , the resourcesthat f low through them, the ways in which they constrain the activit ies ofothers, and the indirect access they give to the resources of third parties(Wellman, Carr ington , a nd H al l , Cha pter 6; Bo d e ma n n , Ch a p te r 8; H o w a r d ,Chap te r 7).T h e possibili ties for indirect ties are a bu nd an t because each direct t ie l inks

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    42 Barry Wel lmantw o concrete individuals and no t just tw o roles . Jack and J i ll are l inked bym ore than a single pail of water . Al though the ro le re la tionship between tw omembers affects expectat ions for behavior , indirect t ies are not necessari lyrestr icted to a s ingle role system: Network members typically use a widevariety of direct and indirect t ies to search for resources, of ten traversingseveral sets of role relat ionships (Milgram, 1967; Lee, 1969; Travers andM ilgram , 1969; Gra nov et ter , 1974; Lin , 1983) . For ins tance, on e ne ighb orof ten asks ano the r to a pp roa ch a local pol i t ic ian for help in deal ing wi th c i tyhall. It is the overall s tructural context of ne twork members tha t def inesspecif ic ties (Burt , 1980, 1982; Feld, 1 981). Hen ce, such p he no m en a aspatron-clien t t ies mu st be treated as local manifestat ions of larger classs t ruc tu r e s ( Bo d em an n , Chap te r 8 ) .

    3. T h e st ruc t uring o f soc ia l t ie s c rea tes non rand om ne t w orks , henceclus ters , boundar ies , and cross -l inkages .

    I s tar t wi th two weak assumptions . The f i r s t i s that t ies in networks areoften t ransi t ive . If th ere is a tie fr om A t o B a n d f r o m B t o C, then there is a nimplici t indirect t ie from A to C - a n d an increased probabi l i ty of theform at ion of a d i rec t tie a t som e t ime in the fu ture . For exa m ple , fr iends off r iends a re mo re tha n ran dom ly likely to be f ri ends and no t t o be enemies o rno t d irect ly l inked (Davis , 1970; Ho l land an d Le inha rdt , 1977) . T hi st rans it iv i ty a rgum ent can app ly to a ll ne tw orks a nd no t just to ones comp osedof f r iendship ties. If there are t ran sfer (o r brok erag e) cos ts , so tha t each no defal ling a long a pa th th rough a ne tw ork consum es som e of the resource f low,the n netw ork me mb ers m ay often f ind i t m ore eff icient t o ma inta in direct ties .

    M y second we ak as sum pt ion is tha t the re a re finite limits t o t he n u m b e rand in tens i ty of t ies that an individual can mainta in ( an d t ha t m o s tind iv idua ls a re near these l imi t s ) . Consequen t ly , mos t peop le canno t addmany new ties (o r add new s t ran ds to ex i st ing t ies) wi thou t g iv ing up som e oftheir exis t ing ties (Pool an d Kochen, 1978) .

    Because of trans i tiv i ty an d reciproci ty , tw o l inked netw ork m em bers of tendraw on o ther s wi th whom they a re jo ined in to a dense ly kn i t c lus te r(Abelson, 1979; Car tw r ight and H ara ry , 1979; Mi lard o, 1982) . F in ite l imi tsop era te so that involvement in d ense c lus ters of ten enta i ls the loss of o the rt ies. Jo in t ly , these s t ructura l processes en cou rage the fo rm at io n of t ies wi th inclus ters and few t ies across boundar ies . A c lus tered network of th is k indcon t ras t s marked ly w i th a r a n d o m n e t w or k in wh ich each m em be r is equallyl ikely to be l inked with ea ch o th er m em ber , o r wi th a c lus ter less evenn e t w o r k , in which each m emb er has the same num ber of l inks (E rdos andSpencer , 1974; Hol land and Leinhardt , 1979b; Rapopor t , 1979; Ryt ina andMorgan , 1982 ; Laumann , Marsden , and P rensky , 1983) .

    Transit ivi ty is a weak assumption. If i t were not , the world might wellco l lapse in to one g ian t c lus te r (Mi lg ram, 1967) . Ne twork members o f ten

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    Structural analysis: from m eta ph or to substanc e 43avoid some direct ties in order to maintain structural autonomy - forinstance, when prodigal sons retain links to their parents through theirbrothers. Some direct ties are structurally difficult to maintain - such asfriendships with feuding coworkers. Intransit ivi ty helps to separate indiv-iduals from one another under these circumstances and to perpetuate discretenetwork clusters (White, 1966; Bernard and Killworth, 1973; Killworth,1974).

    Clustered networks have paradoxical implications for the integration ofsocial systems: "At the level of the individual, the system is highly connected,for he lies at the center of a dense network of direct and indirect socialrelationships. At the level of the total system it is highly disconnected, forthere are many pairs who have neither direct nor indirect relationships"(Davis, 1967: 186). This sort of pattern may well have been the principalstructural reason why the Italian-American residents of Boston's West Endwere unable to form coalitions to defeat the massive "slum clearance"activities that destroyed their neighborhood in the late 1950s (Gans, 1982; seealso Granovetter, 1973).

    Yet not all network ties are bound up in clusters. Since both finite limitsand reciprocity are weak assumptions, individuals are usually members ofmultiple social networks, and their ties can connect clusters. Both cross-linked "cosmopolitans" and internally linked "locals" transmit information,influence, and material resources through a network (and its cluster) incomplementary ways (Gouldner, 1957; Merton, 1957). Cross-linkages giveclusters within a network access to external resources and provide thestructural basis for coalitions. Internal linkages within a cluster allocateresources and provide the structural basis for solidarity.

    4. Cross-l inkages connect clusters as well as individuals .The nodes in a network d o not have to be individual persons. They can be

    sets of nodes, groups, nation-states, or other discriminable units (Friedmann,Chapter 11; White, Chapter 9 ) .The ties in such networks may result fromindividuals' membership in several clusters or because certain persons have"foreign relations" with other portions of the network. Although theobservable ties may often be between individual persons, their importancelies in the fact that they form links between clusters (Bonacich and Domhoff,1981; Breiger, Chapter 4). "The great promise of the network perspective isthat micro and macro can be linked by examining the structural constraintsimposed by relational configurations" (Rytina and Morgan, 1982: go).

    Consider the case of interlocking corporate directorates. What is usuallymore significant is that a director links two corporations, rather than thatcommon board membership is shared by two directors. For example, if theofficers of property development companies are also members of the board ofa public housing agency, the links may enable the companies to acquire

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    Barry Wellman

    Figure 2.4. A network of networks. (a ) Ties between individuals;(b) ties between network clusters.

    "inside" information about public housing activities. When most of themajor companies are represented on the public housing board, the links arelikely to further the class interests of the industry rather than those of anyparticular company.

    The ties give the managers of the public agency easy access to a "number of'trusted' private firms to which it can subcontract its work. Here, the relevantlinks are clearly between the corporate entities, both public andprivate - although the specific linkages are people, wh o hold directorships onthe boards of both" (Craven and Wellman, 1973: 81; ee also Richardson,1982;Berkowitz, Chapter 18).

    When analysts focus on clusters and the ties between them, they are muchless interested in internal ties within a cluster. If a tie between two clustersexists at all, then all members of one cluster are linked with all members of theother cluster through internal ties within clusters (see Figure 2.4).The linkbetween General Motors and the Morgan Bank is more important analyti-cally than ties between specific corporate directors or internal ties within thetwo corporations.

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    Structural analysis: from m eta ph or t o substance 45Some recent s t ructural methods take into account the number of t ies

    connect ing two nodes or the proport ion of a l l resources f lowing betweenthem. Yet some analysts argue that the most important information iswhether or n o t any sort of t ie exists betwe en nodes. T he y suggest that , giventhe lack of connectivity in m ost social systems, any conne ction th at fa cil i tatesflows of resources within a system is im po rta nt (W hite , 1966; Wh ite et al .,1976).

    5. Asymmetric t ies and complex networks differentially distributescarce resources.

    Given asymmetric ties and bou nded netw ork clusters, resources d o notflow evenly o r ran dom ly in a structure. T h e density of clusters, th e t ightnessof boundaries between them, and the pat terns of t ies within and betweenclusters all structure resource flows. Because of their structural locations,members of a social system differ greatly in their access to these resources.Indeed, unequal access to scarce resources may lead to greater asym m etry inties.

    Asymmetric t ies between nod es a nd clusters conc atena te into hierarchicalnetworks and engen der cum ulative differences in access t o resource s (Dav is,1970). In co ntra st t o ideal m odels of hierarc hies - such as those show n o norganiza tional ch ar t s -a c tu a l ne tworks of ten conta in t ies th a t t ransmi tresources in tw o directions as wel l as comp lex st ruc tures with mult iple an dcyclical paths. Desp ite the fac t th a t they ar e imperfectly h ierarchical, a ctu alnetworks are , how ever, ultimately hierarchical, an d the ir cumulative effect isto distribute resources unevenly.

    Researchers have used network -base d not io ns of hierarchy t o study thepol itical econ om ic dev elopm ent of nat ion-states. Th ey have em phasized theimportance of observ ing asymmetr ic t ies between states, regions, andmult inat ional interest gro up s to explain the na tur e of social s t ructure s withinthese sta tes. So m e researchers have suggested tha t the su ppo sed "bac kw ard-ness" of Third World societies is as much a matter of their t ies with othersocial system s as i t is of th eir in tern al rigidities (W ayn e, 1975; Fr ied m ann an dWayne, 1977). Others have shown the central importance of hierarchicalnetworks in the formation of European nat ion-states (Wallerstein , 1974;Skocpol , 1979) and in the opera t ion of in terna t ional commodi ty markets(Friedmann, 1978, 1982; Chapter 11).Positions as resources. Incumbency in a structural posit ion is i tself a scarceresource because i t determines access to oth er resources. For ex am ple, man ymembers of social systems profi t fr om their posi t ion s as "gatekeepers" o r"brokers." A gatekeeper control l ing access to an org aniza t ion 's leader oftengains wealth, flat tery, influence, use of the organizational resources, andpleasure fro m exercising con trol . A bro ker l inking tw o netw ork clusters often

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    46 Barry Wellmantakes a share of the resources pass ing through tha t pos it ion . Indeed, a can nybroke r may impede t rans it iv ity by work ing to prevent the format ion of d irec tl inks between c lus ters . Brokers , by v i r tue of thei r s t ructura l locat ion , ca nn otbe full mem bers of any o ne c lus ter . Of ten thei r very marginal i ty me ans th atthey a re no t fully trusted because n o on e cluster can exercise effective socialcontro l over the m (G offm an, 1963; M ars de n, 1982,1983; Brym, Cha pte r 13) .Flows through p ositions. Persons as well a s resources f low th rough ne tw ork sas they chan ge s t ructura l pos i tions . Th e flows of persons throug h pos i t ionsan d pos i tions thro ug h persons are "duals" (Breiger, C ha pte r 4) . Indee d,posit ions may experience social mobil i ty when persons with differentresources occupy them . Individual moves are pa r t of l inked "vacancy chains"(White , 197oa) . Old incumbents vacate pos i t ions by moving to new ones .H enc e, vacancies also flow thr oug h systems. Several s truc tura l analysts haveused the f lows of persons through posit ions to analyze mobil i ty inocc upa tions, organiz ations , and housing (W hi te, 1970a, 1971; M ullins, 1972;Breiger , 1981; Aminzade and Hodson, 1982; Tolbert , 1982; Stewman andKond a , 1983; Lev ine an d Spadaro , Ch ap te r 17), and demo graph ic cons t ra in t son f lows of cohor ts through socia l sys tems (Howel l , 1979, Chapter 3 ;T e p p e r m a n , C h a p t e r 1 5 ).

    6. Ne two rks structure collaboratiue and co mp etitiv e activities t osecure scarce resources.

    Stru ctur ed com pet i t ion fo r scarce resources is inherent in social systems. Ina sys tem with l imi ted resources, in teres t grou ps comp ete for access t o them .In h ierarchical netwo rks w i th asymm etr ic t ies , mem bers m ust use col labo ra-t ive o r comp lem entary ties t o gain access to these sam e resources . Clus teringwithin a network organizes these t ies in to more or less bounded coal i t ionsand fact ions .

    N etw ork analys ts have wo rked to sh ow th e s tructura l bas is of collec t ivepoli t ical act ivi ty. They have demonstrated how acts of collect ive violence,such as foo d r io ts o r rebel l ions , are in tegra l par ts of broad conten t ions forpo w er by different interest gro up s. Th o se engage d in collective violence arenot the uprooted , d isconnected individuals whose puta t ive exis tence hasfascinated "mass society" theorists .' O n the con trary , tho se m ore deeplyroo ted and more dense ly kn i t in to con tend ing g rou ps a re more likely t o bepolitically activ e - violently a s well as nonv iolently (Brym , C ha pt er 13; Til ly,1967, 1975, 1979, Ch ap te r 12; Feagin, 1973; Sh ort er an d Tilly, 1974;Oberschall, 1978; Snyder, 1978).

    Compet i t ion for resources may lead to change in socia l s t ructure .Coal i t ions and fact ions shif t in t ime, and network real ignments can havebroad systemic consequences (Nic holas , 1965; W hite and M cC an n,C ha pte r 14) . For exam ple , wh en local leaders in India t ran sfer a l legiance

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    Structural analysis: from m eta ph or t o substance 47from one regional pat ron to an oth er ( in itself a n ou tco m e of the al ternat ivesources of reward s available in a n et w or k) , this causes profo un d shifts in thesocial interactions of all their clients, since the se clients, them selves, f or m a n drelinquish network ties (Mayer, 1966; Pettigrew, 1975).

    Although such ne tw ork realignm ents re distr ibu te access to resources, theydo not cause major changes in the division of labor within a social system.Social scientists hav e had gre at difficulty ex pla inin g the co nd ition s fo r suchchanges, either w ithin single states or larger soc ial units.? Since M a rx , ma nyhave argued that s t ructured competi t ion for scarce resources createsconditions for large-scale social change, bu t they ha ve n o t clearly set fo rth themechanisms thro ugh wh ich these changes ta ke place.

    Network modeling techniques may well prov ide useful tools for s tudyin gthese mechanisms. Blockmod eling, for exam ple, ca n prov ide a set of rules forthe transformation of one structure's "image" - a simplified set of rolerelationships - nto another (Boorman and White, 1976; Pat t ison, 1980). I fanalysts can integrate such rules with more strictly historical work bymodeling the condit ions under which system members mobil ize to claimscarce resources (Til ly, 1978), the c om binat io n should imp rove o u r under-standing of large-scale str uc tura l chan ge.

    The state of the artStructural analysis ha s bec om e self-conscious an d organize d. Intellectually, ithas moved from a minimalist po si t ion, wh ere "network analysis" w as seen asa useful supplementary method, to a more maximal is t , paradigmat icposition, where its central concept - hat a l l socia l phenomena are bes tstudied through methods designed to uncover basic social structure - s seenas an importa nt new ap pro ac h to social inquiry. In add it ion to i ts cr i tiques ofother sociological approaches, s t ructural analysis has now developed acoherent set of characteristics an d principles back ed up by a sizable body o fempirical w ork . Institutionally, i t is bolstered by a professional society, tw ojournals, and frequent conferences.

    The m ost s ignificant substan t ive achievements of s tructu ral analysis hav ebeen to pose new intellectual questions, collect new types of evidence, andprovide new ways to descr ibe and analyze social s t ructures . Structuralanalysts have ma ppe d the inter locking t ies of corp orat ion s, s tate s , an d w orldsystems in unders tandab le an d useful w ays , and they have found ab un da ntevidence of "community" by look ing for it in ne tw ork s rat he r th an inneighborhoods. T h e s t ructura l appro ach has revealed powerful wa ys of usingconsistent analyt ic f ram ew orks in linking "micro" netw orks of interperson alrelations with "macro" struc ture s in large-scale social systems.

    Structural analyt ic thought has diffused widely in recent years among

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    48 Barry Wellmanmany sociologists (and other social scientists) who do not identify themselvesas structural analysts. There is increasing recognition in mainstream workthat the proper business of sociologists is the direct study of social structureand not indirect attempts to approach structure through the study ofinternalized norms, individual actions, and dyadic behavior.

    The methodological advances of structural analysis have been impressive.Not only have structural analysts mounted an effective critique of thelimitations of individual statistical techniques, they have produced a batteryof concepts, methods, and techniques better suited to comprehendingstructures and relationships. T o date, the strangeness and mathematicalcomplexity of their approach has kept it from being widely adopted. Yet,its use is spreading widely, and many structural methods have workedtheir way into the tool-kits of those initiated into the higher mathe-matical arts.

    The explanatory achievements of structural analysis have been moreuneven. Although the general utility of its emphasis on studying socialstructures depends, to some extent, on one's aesthetic preferences, the specificutility of the more precise principles and methods of structural analysisdepends to a greater extent on its success in providing more powerful analysesthan other approaches to interpreting social phenomena. Here the results arenot yet clear. This is because structural analysts often have not competeddirectly with other sociologists in explaining the same phenomena. Rather ,they have been preoccupied with reformulating basic questions. They haveproposed, for example, substituting world-systems analysis for single-statemodernization theories, network communities for neighborhood commun-ities, political networks for psychologistic interpretations of collectivebehavior, and vacancy-chain analyses for individualistic analyses of socialmobility.

    Th e current state of structural analysis is probably just a way station on theroad to more comprehensive formulations. This chapter has reasonedupward, working from the characteristics of ties toward those of largernetworks. By contrast, a more thoroughgoing structural formulation wouldhave reasoned downward, working from the properties of large-scale"networks of networks" to the nature of clusters and ties. For example, suchan approach might have systematically analyzed the nature of family andcommunity networks within the constraints of capitalist or socialisteconomies. Sociologists are just beginning to advance beyond intuitiveways of doing such top-down analyses. To date, the success of theirwork has often depended heavily on the persuasiveness of their verbaldescriptions. Here, too, the facility of structural analysts in posingquestions would be enhanced by an increased ability to provide valid andreliable answers.

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    Structural analysis: from metaphor to substance 49N O T E S

    I . Rosch and Mevis, 1975, have argued for the pervasiveness and usefulness ofdefiningcategories thro ug h "fam ily re semblan ces." 1 follow their app ro ac h in thischapter by defining "structural analysis" in this fashion. Note that in stressingnetworks of l inkages between categories , the family resemblances approach tocognition is i tself analogo us to so m e forms of s tru ctural sociology. Exa mp les ofrecent efforts to provide a s tan da rd text are L einha rdt , 1977; Rogers an d Kincaid ,1981; Berkowitz, 1982; Burt , 1982; Knoke and Kukl insk i , 1982. Bibliographiesinclude: Freeman, 1976; Feger , Hummel , Pappi , Sodeur , and Ziegler , 1982;Scherer, 1983. These wo rks complement the p resen t chap te r, a s d o th e di scuss ionsby Mullins, 1973; H o w a r d , 1974; W hite , Boorman, and Breiger, 1976; L a u m a n n ,1979;Berkowitz and He il , 1980; Bur t , 1980; Laum ann e t a l., 1983; Pat t ison, 1980;Alba, 1981. Conn ect ions , the inform al journal of the Internat ional N etw ork forSocial Ne two rk Analysis (IN SN A ), an d Social N etw ork s, a refereed journal ,provide contemporary coverage.

    z. 1mean "British" in th e intellectual sense; tha t is , mo st o f the anthrop ologists weretrained o r based a t British univ ersities. M an y of their orig ins (e.g. , A ustra lia,Canada, and N ew Z eal an d) and a rea s of s tudy (e.g., Africa and India) wer e of theold and new Empire.

    3. For summaries and reviews of this work see Srinivas and Beteille, 1964; Mitchell,1969a, b, 1973b, 1974, 1979; Bott, 1971; Barnes, 1972; Boissevain, 1974, 1979;Whitten and Wolfe, 1974;Wolfe, 1978. Nu m erou s case s tudies and analyses exist ,e.g., Mitchell, 1956, 1961, 1969c; Gutkind , 1965; Wolf, 1966; Mayer , 1966;Liebow, 1967; Epstein, 1969; Parkin , 1969; Wa yne , 1971: 51-2; Kapferer, 1972;Boissevain and M itch ell, 1973;Jacobson, 1973; Roberts , 1973; Ma ye r w i th M a ye r ,1974; Boswell, 1975; Peil, 1978, 1981; R obe r t s , 1978; Peatt ie and Rein, 1979.

    4. For example, analys ts have m apped th e s t ruc tu re of in te rcor por a te re la t ions inAmerica (Levine, 1972; Soref, 1979; Bur t , 1982; Mizruchi , 1982; Min tz a ndSchwartz, 1985); Ca na da (Berkowi tz, Car r ing ton , Kotowi tz , and W averman,1978-9; Carr ington, 1981; C a r ro l , F ox , a nd Orns t e in , 1982; Orns t e in , 1982;Richardson, 1985); Europe (Scot t , 1979; Stokrnan, Ziegler , and Scot t , 1985); andthe entire western industrial wo rld (Levine, 1984).

    5. For s tudies of urb an personal comm unit ies , see, Lau m ann , 1973; Shulman, 1976;Fischer, Jackson, Steuve, Gerson, Jones with Baldassare, 1977; Verbrugge,1977; Wellman, 1979, 1985;Fischer, 1982;G r e e n b a u m , 1982; H o w a r d , C h a p te r 7;Wellman, Car r ing ton , and H a l l , Cha pte r 6. Fo r stu dies of re sou rce access, see Lee,1969; Griff i th and Mil ler , 1970; Gra nove t t e r , 1974; B o o r m a n , 1975; Mull ins ,Hargens, Hech t , an d Kick, 1977; C a lz a va ra , 1982; Lin, 1983; Delany, Chapter 16.For s tudies of social support , see Gott l ieb, 1981; Hirsch, 1981; H a m m e r , 1983;Kadushin, 1983; Brownel l and Shumaker , 1984; C ohe n a n d S ym e 1985; Sarasonand Sarason, 1985; Lin, Dean, and Ensel , 1986.

    6. These seven po in t s a re based , in pa r t , on H ow ard , 1974: chap . I .7. See Hea th, 1976; K a ~ f e r e r , 976; Burgess and Hu ston , 1979. For work integra t ing

    exchange theory into s tructural analysis , see Emerson, 1981; C ook , E m e rs on ,Gilmore , and Yamagishi , 1983; a n d M a r sd e n , 1983.

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    50 Barry Wellman8. Fo r exam ple, Davies , 1962; K orn hau ser , 1968; G urr , 1969. Will iam R ya n (1971)

    cal ls such s ingle-unit expla nat ion sof Am erican race re la t ions "blaming the vic tim."9. For exa m ple , th e develop m ent of the capi ta l is t "world system," Wal lerste in , 1974.

    Also see Fr iedmann, Ch apte r 11.

    L I T E R A T U R E C I T E DAbelson, Ro be r t P. "Social Clusters and O pin ion Clusters ." In Paul H ol lan d an d

    Samuel Le inhard t (eds .) , Perspect ives o n Soc ia l Ne two rk Research . Ne w Yo rk:Academic Press, 1979.

    Alba , Richard D. "From Smal l G rou ps to Soc ia l Netwo rks ." Amer ican B ehaviora lScien tist 24 (198 1): 681-94.

    "Tak ing Stock of N etw ork A nalysis : A Decade 's Results." In Samuel Bac harach(ed.) , Perspectives in Organ izational Research. G reenw ich, C on n: JAI Press,1981.

    Alba , Richard , an d Gw en Mo ore . "El ite Social Circ les." Sociological M eth od s an dResearch 7 (1978): 167-88.

    Aminzade, R ona ld , and Ra nd y Hodso n . "Social Mo bi l ity in a Mid-n ine teen thCe ntu ry Fre nch City." Am erican So ciological Review 47 (1982): 441-57.

    Anderson , M ichae l. Fami ly St ruc ture in Nine teen th Century L ancashi re . Cam br idge :Cambridge Universi ty Press, 1971.

    Arabie , Phipps, Scott A. Boorman, and Paul R. Levi t t . "Constructing Blockmodels :H o w and Why." Jo urn a l o f M athem at ica l Psychology 17 (1978):21-63.

    Back ma n, Car l . "Attraction in Interpersonal Relat ions ." In M orr is Rosenb erg an dRa lph T ur ne r (eds .) , Social Psychology: Sociological Perspectives . N ew Y ork :Basic Books, 1981.

    Barnes , J. A. "Class and Com m it tees in a Norw egian I s land Parish." H um anRelations 7 (1954): 39-58.

    Three Styles in the Study of Kinship. London: Tavis tock, 1971.Social Networks. Reading, Mass . : Addison-Wesley, 1972.Berkowitz , S. D. "Structural an d N on -stru ctu ral M od els of Elites ." Ca nad ian Jo ur na l

    of sociology 5 (1980): 13-30.An In t rod uc t ion to S t ruc tura l Ana lys is . To ron to : B ut te rwor ths , 1982.

    Berkowitz , S. D., an d Grego ry Hei l. "Dual i t ies in M eth od s o f Social Ne tw orkResearch." W ork ing Paper 18 ( revised) ,Structural Analysis Program me , U niver-s i ty of Toronto, 1980.

    Berkowi tz , S . D. , Pe te r J . Car r ing ton , Yehuda Kotowi tz , and Leonard Waverman."The Determina t ion of Ente rpr i se Groupings through Combined Ownersh ipan d D irecto rship Ties." So cial N etw or ks (1978-79): 75-83.

    Bernard , H . Russe l l, and Pe te r Ki l lwor th . "O n the Soc ia l S t ruc ture of an O cean -Go ingRese arch Vessel and O th er Im po rtan t Things." Social Science Research z(1973 ): 145-84."A Review of the Smal l W orld Li tera ture." Con nections 2 (1978): 15-24.

    Berscheid, El len, and Elaine Walster . Interpersonal Attraction. Reading, Mass:Addison-Wesley, 1978.

    Blok, A nton . T he Mafia of a Sicil ian Village, 1860-1960. N ew Y ork: H arp er a n d

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    ship." Social Networks 3 (1981): 175-96.Boorman, Scott A. "A Co m bina toria l Op tim izat io n Model for Transmission o f Jo b

    Information through Contact Networks." Bell lournal of Economics 6(1 9 5 ): 216-49.

    Boorman, Scott A. a n d Pau l Levitt. Th e Genetics of Altruism. N ew York: AcademicPress, 1980.Boorman, Scott A., a nd H arris on C. W hite . "Social Stru ctur e from Mu lt ipleNetworks 11: Role Structures." American lournal of Sociology 81 (1976):1384-1446.

    Boswell, David M . "Kinship, F riends hip an d the Co ncep t of a Social Netw ork." In C .Kileff a nd W . C . Pen dleton (eds.), Ur ban M an in Southern Africa. SignalMountain , Tenn. :M a m b o Press , 1975.

    Bott, Elizabeth. Family and Social N et w or k. Lon don : Tavisto ck, 1957; 2nd ed., 1971.Breiger, Ronald L. "To w ar d an Op erat iona l T he or y of Co mm unit y Eli te Structures."

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    Burgess, Robert L. , and Ted L. Huston (eds. ) . Social Exchange in DevelopingRelationships. New York: Academic Press, 1979.

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