Social Ties and WOM Referrals Behaviour

Journal of Consumer Research Inc.

Social Ties and Word-of-Mouth Referral BehaviorAuthor(s): Jacqueline Johnson Brown and Peter H. ReingenReviewed work(s):Source: Journal of Consumer Research, Vol. 14, No. 3 (Dec., 1987), pp. 350-362Published by: The University of Chicago PressStable URL: http://www.jstor.org/stable/2489496 .Accessed: 29/11/2011 21:07

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Social Ties and Word-of -outh

Referral Beav or*

JACQUELINE JOHNSON BROWN PETER H. REINGEN**

This article presents a network analysis of word-of-mouth referral behavior in a natural environment. The relational properties of tie strength and homophily were employed to examine referral behavior at micro and macro levels of inquiry. The study demonstrates different roles played by weak and strong social ties. At the macro level, weak ties displayed an important bridging function, allowing information to travel from one distinct subgroup of referral actors to another subgroup in the broader social system. At the micro level, strong and homophilous ties were more likely to be activated for the flow of referral information. Strong ties were also perceived as more influential than weak ties, and they were more likely to be utilized as sources of information for related goods.

OffImne of the most widely accepted notions in con- k-isumer behavior is that word-of-mouth communication (hereafter WOM) plays an important role in shaping consumers' attitudes and behaviors. In an early study, Whyte (1954) investigated the diffusion of air conditioners in a Philadelphia suburb. He concluded, on the basis of anecdotal evidence, that the pattern of ownership could be explained only by the presence of a vast and powerful network consisting of neighbors exchanging product information in contexts such as "over the clothesline" and "across backyard fences." Subsequent investigations of the WOM phenomenon produced more formal statistical confirmation of its importance. In one of the first, more formal studies, Katz and Lazarsfeld (1955) found that WOM was the most important source of influence in the purchase of household goods and food products. It was seven times as effective as newspapers and magazines, four times as effective as personal selling, and twice as effective as radio advertising in influencing consumers to switch brands.

In the years ensuing the advent of television as a major medium of promotion, many other studies that were conducted primarily during the 1960s and early 1970s

demonstrated the continued importance of interpersonal influence. For example, Engel, Blackwell, and Kegerreis (1969) found that almost 60 percent of the respondents who could recall the most influential source regarding their adoption of an automotive diagnostic center named WOM; Feldman and Spencer (1965) determined that about two-thirds of new residents in a community relied on WOM to select a physician; and Arndt (1967) showed that respondents who received positive WOM about a new food product were much more likely to purchase it compared to those who received negative WOM. More recent published research is rare (e.g., Richins 1983).

These studies have contributed significantly to the cumulative understanding of WOM behavior. However, it appears that a considerable potential exists for enriched conceptualizations and new research directions on WOM. These are essential in addressing several significant gaps in understanding WOM phenomena that exist at the macro level of inquiry (e.g., flows of communication across groups), as well as the micro level (e.g., flows within dyads or small groups). At the macro level, there is a severe lack of understanding of several important issues, including how WOM interaction in dyads or small groups aggregates to form large-scale patterns in the diffusion of information and influence concerning innovations, existing products/services, fashions, fads, rumors about products, and the formation of widely held consumer attitudes. At the micro level, very little is known about a variety of WOM aspects, such as which interpersonal ties are more likely to be activated for the flow of information and which activated ties are more influential in consumers' decision-makino.

*This article was a finalist in the 1987 Robert Ferber Award for Consumer Research competition for the best interdisciplinary article based on a recent doctoral dissertation. The award is cosponsored by the Association for Consumer Research and the Journal of Consumer Research.

**Jacqueline Johnson Brown is Assistant Professor, Department of Marketing, University of San Diego, San Diego, CA 92110. Peter H. Reingen is Professor, Department of Marketing, Arizona State University, Tempe, AZ 85287. The authors thank William C. Gaidis and the anonymous reviewers for their constructive comments.

Iss ? JOURNAL OF CONSUMER RESEARCH a Vol. 14 e December 1987

WORD-OF-MOUTH NETWORKS 351

There are several underlying reasons for these gaps in understanding. Though WOM behavior arises from and is constrained by consumers' social relations with others, the typical WOM study does not undertake a relational analysis of WOM processes precipitating out of interpersonal networks. This is not only characteristic of the research on interpersonal communications in consumer behavior. Rogers (1983), for example, posits the lack of sociometric analysis as a major shortcoming of the many hundreds of diffusion of innovations studies. In addition, in consumer behavior as well as diffusion of innovations, there is almost never an attempt to directly trace information flows along paths of interpersonal ties, although many investigators have em- phasized the need for such research (e.g., Reynolds and Darden 1971; Sheth 1971). Hence, how micro-level interactions in dyads or small groups aggregate into large- scale processes eludes us in most cases (Granovetter 1973).

Another major (probably related) reason for these gaps in understanding is that appropriate theory and methods for addressing them were either unavailable or not widely known at the time when most of the WOM research in consumer behavior was conducted. Since that time, several conceptual and methodological advances have occurred in a number of disciplines. On the conceptual front, the notions of tie strength (i.e., intensity of a social relation between consumers) and homophily (i.e., communication between similar consumers) have become popular. They appear to be par- ticularly promising for enhancing the present understanding of WOM behavior because these concepts address properties of social relations from which WOM behavior arises. Since WOM is a social phenomenon, properties of social relations are likely to play a crucial role in WOM behavior at micro as well as macro levels of inquiry. In terms of methodology, network analysis has been developed into a powerful method for inves- tigating linkages between micro-level social phenomena and macro-level processes (see Burt 1980; Knoke and Kuklinski 1982; and Wellman 1983 for excellent reviews of network analysis). Granovetter (1973, p. 1360) argues that in one way or another, it is through interpersonal networks "that small-scale interaction be- comes translated into large-scale patterns, and that these, in turn, feed back into small groups."

PURPOSE AND FOUNDATIONS

The purpose of the present study is to examine, from an interpersonal network perspective, the roles that tie strength and homophily may play in macro and micro WOM processes. The specific type of WOM behavior examined here is referral communication-a common, yet underresearched WOM phenomenon.

Before the study is presented, however, it is beneficial to explore by means of an example several of its conceptual and methodological underpinnings. Figure A

FIGURE A

EXAMPLE NETWORKS

NOTE: Referral relations (directed lines) are depicted along a time dimension. Interpersonal ties in more densely knit network segments (subgroups composed of referral actors) are indicated by nondirected lines. For illustrative purposes, suppose the referrals involve a financial

planning service. Further suppose that referral actors A, B, and C are friends living in the

same neighborhood (strong ties), E, F, and G are also friends employed by the same company, and that the AD and BE ties represent acquaintance relations (weak ties).

portrays hypothetical referral flows embedded in a sub- set of a larger social system for a particular service (see the note to Figure A for a description of the scenario). It provides a context for the discussion of two basic issues: (1) the distinction between a WOM relation and the form of relation from which WOM behavior arises, and (2) the problem of network delimitation in the kinds of open systems that are characteristic of most consumer behavior contexts.

Relational Content and Relational Form The relations exhibited in Figure A have both content

and form, resulting in two networks. The first network is the referral network based on relational content (directed lines). In general, relational content refers to the substantive type of relation represented in the connec- tions among individuals. The content type in the example is a communication relation by which messages are transmitted from one consumer to another on "who- told-whom-about-the-service" paths of referral flow. The second network (nondirected lines) is based on relational form. Relational form refers to properties of the linkage between pairs of actors that exist indepen- dently of specific contents (Knoke and Kuklinski 1982). One fundamental aspect of relational form illustrated in the example is tie strength (Burt 1982). Tie strength is indicated by several variables such as the importance attached to the social relation, frequency of social contact, and type of social relation (e.g., close friend, acquaintance; Granovetter 1973; Weimann 1983). Tie strength is a continuous variable, but in the example ties are shown as either strong, weak, or absent, which is customary in the research on this topic.

Conceivably, relations may be identical or highly similar in content but quite distinct in form. This is illustrated in Figure A where a consumer (A) refers the service to a weak tie (an acquaintance D) as well as a

352 THE JOURNAL OF CONSUMER RESEARCH

strong tie (a close friend B). It is also possible that relations may be identical or highly similar in form but different in content. For example, a consumer (A) in Figure A refers the service to a consumer (B) but not to another individual (C), although all of these actors are in strong-tie relations with each other. Thus, relational content (referral communication here) and relational form (tie strength) have different conceptual connotations.

Boundary Delimitation The capacity of network analysis to isolate more

densely knit network segments (A, B, C and E, F, G in Figure A) allows for the investigation of how small-scale interaction aggregates to form larger-scale patterns (see the tie between consumers B and E, which was a crucial bridge for the diffusion of referrals from one of the segments-A, B, C-to the other-E, F, G). However, network analysis (as any method) is not without problems. One of the most significant challenges facing the network analyst in the study of WOM processes in the kinds of open systems that characterize most consumer behavior contexts is that of boundary specification: Where does one set the limits on networks that may have no obvious boundaries? Many network analyses have been performed on formally bounded systems (in consumer behavior, the Arndt (1967) study of WOM behavior in a student housing project and the Reingen et al. (1984) investigation of brand congruency among sorority sisters are examples of this approach to boundary specification). Though extremely useful for many purposes, this approach to setting limits on networks may solve the boundary problem in appearance only. This is apparent when an investigator who examines WOM processes in a village, for example, arbitrarily omits WOM relations that occur outside the village and those that assume boundary spanning roles. If these relations somehow condition WOM behavior in the village, conclusions based on within-village observations alone may be inappropriate.

In general, delimiting network boundaries depends to a great extent upon an analyst's purposes (Knoke and Kuklinski 1982). Similar to previous network analyses performed on essentially open systems such as elite social circles (Alba and Moore 1978), information flow chains in urban environments (Erickson et al. 1978; Granovetter 1973; Reingen and Kernan 1986), and community influentials (Laumann and Pappi 1976), the approach to boundary specification in Figure A is based on mutual relevance. According to this criterion, the system in Figure A includes only those actors who are relevant to each other because of their participation in the same event or activity (i.e., referrals). Obviously each actor has many more interpersonal ties than are shown in Figure A, but individuals who are not participants in referral behavior are excluded because they are not directly relevant to the investigation of referral

flows. This is the approach to boundary specification taken in the present study.

The hypotheses tested in this study are presented next, starting with an examination of the role of tie strength in the flow of referral information across subgroups re- siding in a broader interpersonal network composed of referral actors. All hypotheses are based on explicit reference to WOM referral behavior as the criterion of common relevance to the WOM participants.

HYPOTHESES

Strength of Weak Ties Granovetter's ( 1973) theory on "the strength of weak

ties" provides a promising explanation of the process by which WOM behavior at the micro level is linked to macro-level phenomena. A consumer's social relations with other relevant actors typically include a spectrum of ties ranging from strong primary (such as close friends) to weak secondary (such as seldom-contacted acquaintances). The few consumer behavior studies with a direct focus on communication flows in interpersonal networks obtained results for only the strong ties (Arndt 1967; Leonard-Barton 1985). This is consistent with the general tendency of researchers to view weak ties as trivial or to simply overlook them. Granovetter (1973) claims, however, that weak ties play a crucial role in clarifying and explaining a variety of social phenomena. For WOM referrals, this "strength of weak ties" arises from their important bridging function that allows information to travel from one densely knit "clump" of social structure composed of referral actors (A, B, C in Figure A) to another more cohesive segment of the broader referral system (E, F, G in Figure A) through a weak tie (B and E). If weak ties did not exist, a system would consist of disjointed subgroups, inhibiting the widespread diffusion of information. Weak ties, therefore, are potentially important in examining how interaction at the dyadic level aggregates to form a large-scale pattern. It is crucial to recognize, however, that Granovetter does not argue that all or even most weak ties serve as bridges linking closely knit network segments: "The importance of weak ties is as- serted to be that they are disproportionately likely to be bridges, as compared to strong ties, which should be underrepresented in that role" (Granovetter 1982, p. 130).

Although the theoretical argument of the strength of weak ties is compelling, its empirical verification is on shakier grounds. First, there is the problem of generalizability, because many studies examined the role of weak ties in only one context, namely in individuals' search for a new job (e.g., Granovetter 1974; Lin 1982). Second, and more importantly, Granovetter (1982) notes in his revisions of the theory that many studies did not set out systematically to test the argument of the strength of weak ties. They employed the argument


to explain empirical findings that otherwise would have been anomalous, and "furthermore, a number of the studies . . . are mainly theoretical, proposing that, in their subject area, weak ties can be seen as serving important functions, but not actually bringing any sub- stantial body of empirical data to bear on this assertion" (Granovetter 1982, p. 129). To empirically verify the strength of weak ties, one needs to show not only that ties bridging network segments are disproportionately weak but also that something flows through these bridges; they actually serve as conduits bringing information to subgroups that they would otherwise not obtain. The few studies in sociology that put the argument to a direct test (e.g., Friedkin 1980; Weimann 1983) provide encouraging but inconclusive evidence (Gra- novetter 1982). In consumer behavior, direct evidence linking the strength of weak ties to the flow of information through WOM channels of communication appears nonexistent. Thus, the following hypothesis is tested:

HI: Weak ties activated for a referral are more likely than strong ties to serve as bridges through which WOM referrals flow.

Strength of Strong Ties Granovetter (1982, p. 113) acknowledges in his re-

visions of the theory "that strong ties can also have some value." However, little research has focused on the circumstances when strong ties play their unique role. Whereas weak ties may be crucial in explaining macro phenomena of interpersonal communication (e.g., flows of information across groups), our general proposition is that strong ties play a more significant role in several aspects of micro-level referral behavior, including tie activation, information seeking, perceived influence, emergence of subgroups, and overlap in personal sources of information.

Tie Activation. In many consumer behavior contexts, it is possible that a consumer is in social relations with several other individuals who were prior participants in WOM activity dealing with a good. In Figure A, for example, consumer C has social access to two such individuals (A and B). However, it is unlikely that each tie with these potential sources of information has an equal probability of being activated for the flow of information. A variable potentially affecting tie activation is strength of tie. Since strong ties are typically more readily available and result in more frequent interaction through which the transfer of information may arise, the following hypothesis emerges:

H2: When a consumer is in social relations with both strong and weak ties who are available as potential sources of referral, strong ties are more likely than weak ties to be activated for the referral flow.

Information Seeking. Hypothesis 2 did not in- corporate aspects of the circumstances prompting tie activation. Activating a tie for information flow may be due to several reasons, including actively soliciting information from a source or flows induced by situational or environmental cues (Belk 1971). Strong-tie consumers will probably know much more about each other than do weak-tie ones, including how relevant they are to each other as sources of information about consumer goods. This should facilitate active information search behavior among consumers in strong-tie relations, resulting in the following hypothesis:

H3: Active information seeking is more likely to occur from strong-tie than weak-tie sources of referrals.

Perceived Influence. Ties activated for the flow of information may also vary in the degree of influence as perceived by receivers. Therefore, it is useful to distin- guish between flows of information and perceived influence. As Lin (1971) has observed, the literature on interpersonal communication has often failed to dif- ferentiate between these types of flow. They may be regarded as related but conceptually distinct processes, because the flow of influence plays a more significant role in individuals' decision-making. Research is lack- ing, but strong-tie sources may be perceived as more credible than weak-tie ones (Rogers 1983). This suggests the following hypothesis:

H4: Information from strong-tie referral sources is perceived as more influential in receivers' decision-making than is information obtained from weak-tie referral sources.

Subgroups. Granovetter (1973) argues that strong- tie networks exhibit a tendency toward transitivity. (If person A is linked to persons B and C in a strong-tie network, there is a high probability that the B-C link will also occur). This tendency facilitates the emergence of subgroups of referral actors. Subgroups of this kind have an emergent character, and they tend to be infor- mally structured (Reingen and Kernan 1986). Never- theless, consistent with Granovetter's (1973, 1982) notions of more densely knit "clumps" of social structure, the subgroups have members who have relatively strong ties with each other and who have repeated interactions.

Based on the research dealing with the impact of informal groups on members' brand preferences (e.g., Reingen et al. 1984; Stafford 1966), members in a subgroup composed of referral actors for one good may also have more homogeneous preferences for a variety of other goods than do those who belong to a different or to no subgroup. This may be so because the multiple redundant paths of communication in a subgroup imply that its members are generally more readily available to each other as sources of information and influence. Reingen et al. (1984) obtained several results that are consistent with this notion, but their study was con-


ducted in a sorority setting, guaranteeing that all respondents were in relations with one another. This may have produced a ceiling effect, possibly accounting for the many statistically insignificant results in their study. To circumvent this potential problem, it is beneficial to extend the Reingen et al. (1984) research to a more open social system where many consumers have no direct linkages. Therefore, the following hypothesis is tested:

H5: Consumers with joint membership in a subgroup of referral actors for one good are more likely to prefer the same brand for other goods than are those consumers who belong to a different or to no subgroup.

Overlap. Hypothesis 5 dealt with brand congruency among subgroup members in strong-tie networks. The subgroup was the primary unit of analysis. At the dyadic level of analysis in strong- as well as weak-tie interpersonal networks, strong ties may play another unique role in the extent to which consumers rely upon the same members of the information flow network for one good for obtaining information about a related good. Feldman and Spencer (1965) suggest such overlap in information flow networks, but the role of tie strength has not been previously examined in this context. Since the greater frequency of interaction among strong-tie consumers should enhance the likelihood of information transfer for a variety of goods, the following hypothesis is tested:

H6: Strong ties, who were activated for the flow of referral for one good, are more likely than weak ties to be activated as sources for a related good.

Homophily/Heterophily

The previous discussion focused on how one relational property-strength of tie-may be of value in addressing a variety of issues related to micro-level and macro-level WOM phenomena. Another promising construct capable of providing a conceptually enriched understanding of WOM behavior is homophily.

Homophily is the degree to which pairs of individuals are similar in terms of certain attributes, such as age, sex, education, and social status (Rogers 1983). A fundamental principle of human interaction is that people tend to interact with others who are like themselves; thus, it is also known as the like-me principle (Laumann 1966). Some scholars treat the concepts of strength of tie and homophily as synonymous (e.g., Gatignon and Robertson 1985; Rogers 1983), but our preference is to employ them as separate but related constructs. A distinction between these constructs is that homophily refers to the similarity in attributes individuals possess who are in a relation (e.g., same or different social status), whereas tie strength is a relational property that

manifests itself in different types of social relations varying in strength (e.g., close friend, acquaintance).

Granovetter (1973) suggests that the stronger the tie connecting two individuals, the more similar they tend to be. Direct evidence relating these two constructs to WOM in consumer behavior does not exist as far as is known, but since one would expect weak social ties to be heterophilous, the special significance of heterophilous communication may be that it facilitates the flow of information between diverse segments of a social system. This may help explain why "heterophilous communication has a special informational potential, even though it may be realized only rarely" (Rogers 1983, p. 175). It is hypothesized that:

H7: Weak ties activated for the WOM referral flow of information are more heterophilous than activated strong ties.

Homophily may also play an important role at the micro level of WOM behavior. Since homophilous individuals are more likely to interact with each other than heterophilous ones, homophilous ties may have a greater likelihood of being activated for the WOM flow of information. Thus, it has been suggested that many flows are homophilous (Feick, Price, and Higie 1986; Gatignon and Robertson 1985). It is important to recognize, however, that the typical study for homophily (e.g., Feldman and Spencer 1965) examined merely the ties that were activated for the flow of information (e.g., the AB tie in Figure A) without comparing them to those that could have been but were not activated (e.g., the AC tie). It is suggested that a more valid test of the homophily argument necessitates a comparison between the ties that are activated and those that are not activated for the flow. Finally, homophilous sources of information may be perceived as more credible than heterophilous ones, suggesting that homophilous sources may be perceived as more influential (Rogers 1983). Thus, the following hypotheses emerge:

H8: Of an individual's potential personal sources of information, the more homophilous the tie, the more likely it is activated for the flow of referral.

H9: As homophily of a tie increases, information provided by an activated tie is perceived by receivers as more influential in decision- making.

METHOD

Research Setting The who-told-whom networks of information flow

were traced for three piano teachers. These marketers were located in the same suburban area of a large Southwestern city, and they were in social relations with each other (e.g., all belonged to the same music teacher


association). Since this resulted in a connected graph of social relations among all actors regardless of which initial information diffusion network they belonged to, the diffusion networks for analysis purposes were treated as a single system. There were other similarities across the teachers as well. Each had been teaching full-time for many years, and at the time of the study each had at least 20 current and/or recent-past students. None engaged in formal marketing communication through mass-media channels, and none actively solicited cus- tomers. They instead relied on positive WOM to gen- erate market transactions. Thus, this setting effectively isolated the effect of WOM on behavior. Although the study examined the interpersonal network used by piano students or their parents to select a piano teacher, it is believed that other service providers such as phy- sicians, lawyers, CPAs, hair stylists, and so on may obtain their clientele through similar processes.

Since it was initially unknown who belonged to the referral networks, a two-phase method for collecting the data was required. Briefly, in the first phase, cus- tomers of a service were asked to reveal how they had learned about its existence. When a respondent mentioned another person, that person was contacted and asked the same question. The process was repeated until a WOM path was traced back to a marketer. Respon- dents could include both users and nonusers of the service who had been information sources. The first phase, then, was employed to produce data on just the WOM referral networks. It included only those social actors who were relevant to each other as defined by the substantive questions guiding the research, and system "closure" was obtained through complete backward tracing of WOM referral paths. Once the system was identified, the second phase was conducted. This phase generated data on the social structure among all actors in the system. These data were necessary to examine the flow of referrals across subgroups.

Phase 1 Subjects and Procedure

The initial population under study (n = 67) consisted of 23 of the teachers' current and/or recent-past adult students, 11 teenage students, and parents of 33 students who were under 13 years of age.

These younger students were generally not inter- viewed because careful pretesting on a similar group of young students (n = I 1) of another piano teacher clearly indicated that the information search process as well as the decision to enroll in piano lessons from a particular teacher were typically parental ones (usually performed by the mother of the child). However, in the few instances (n = 3) where the initial interview with the par- ent (most often the mother) revealed that the child was involved in the referral process, an interview was conducted with the child as well. Cross-checks between information provided by these children and their parents showed no inconsistencies in responses.

The 67 initial subjects were sent a preliminary no- tification letter bearing the endorsement of their teacher. A few days later they were telephoned by a carefully trained interviewer. As many callbacks as necessary were made. The respondents were asked how they first learned about their piano teacher. When a subject mentioned another person, an address and telephone number were requested, which were most often provided by the initial respondents. These mentioned individuals were then notified by mail and telephoned by the same interviewer who conducted all of the initial interviews. They were in turn asked how they had first learned about the piano teacher; anyone named as a referral source was similarly contacted. This backward tracing process was repeated until a path could not be further traced.

There were 145 potential actors in the system, but 13 (9 percent) could not be reached, seven (5 percent) mentioned an impersonal source (e.g., a press release about a concert mentioning the teacher), four (3 percent) refused to participate, and three (2 percent) actors had no recall or did not know the source's name. Re- maining were 118 (81 percent) actors who were on referral paths traced back to the teachers, thus qualifying for further inclusion.

At the close of the interview, subjects were asked for a commitment to participate in the second phase of the study. Letters thanking them for their cooperation were sent shortly after the first interview.

Phase 2 Subjects and Procedure To begin the second phase of data collection, a list

of the names of those mentioned as referral participants in the first phase was prepared. A copy of this list was mailed to each of the 118 respondents from Phase 1, along with a cover letter explaining the purpose of the study. Respondents were asked to look through the list, mark those persons that they knew, and keep the list handy so it could be referred to when the interviewer called.

One hundred thirteen of the 118 potential respondents to this phase completed the interview for a response rate of 96 percent. One respondent to Phase 1 refused to participate in Phase 2 and the other four individuals could not be reached after repeated attempts. Most of the respondents were female (87 percent), between 36 and 55 years of age (66 percent), had at least attended college (84 percent), and had lived in the metropolitan area for at least 10 years prior to the start of the study (73 percent).

At the close of this second interview, respondents were thanked for their participation and asked if they would like a nontechnical summary of the results.

Measures Tie Strength. Respondents were asked to identify

the type of social relation with each of the actors they


knew at the time of their WOM behavior. The categories were: friend, neighbor, relative, acquaintance, and other (specify). Data on frequency of communication and importance attached to the relations with those actors were also obtained. Frequency of communication was scaled: daily, weekly, biweekly, monthly, and less than once a month. Importance was measured on a five-point scale with anchors "merely an acquaintance" (1), "not THAT close, but still important" (3), and a person the respondent "feels so close to it's hard to imagine life without him/her" (5).

Homophily. To investigate the hypotheses for homophily, standard demographic questions were asked in both phases about the respondents' occupation, education, age, and sex. Ties were classified as homophilous (heterophilous) when they had identical (different) category memberships for at least three of these demographic measures of homophily. For example, a dyad was categorized as homophilous (heterophilous) when its members had the same (different) categories for occupation, education, and age.

Potential Sources of Information. Respondents were asked in Phase 2 to list all other actors in the system they knew at the time of their information acquisition behavior. Phase 1 yielded information on the time of each respondent's WOM behavior. Only those actors who were known to a respondent at the time of his/her information acquisition behavior and who possessed knowledge of the marketer at that time were considered potential sources of information.

Information Seeking. Respondents were asked in Phase 1 whether they had specifically asked the sender for information (i.e., initiated the conversation to obtain information) or whether the topic had just come up in conversation begun for other reasons.

Perceived Influence. Respondents rated on a five- point scale how influential the information provided by a sender had been on the final selection of their piano teacher (1 = very little influence; 5 = very great influence). Respondents who had several sources of information were also asked to indicate who was the most/ least influential source.

Congruency. To examine brand congruency in subgroups, respondents in Phase 1 were asked to name their preferred restaurant, brand of piano, brand of shampoo, piano tuner, and dentist. To increase the generalizability of findings, these products and services included related/unrelated (i.e., tuner/dentist) and typically publicly consumed/privately consumed items (e.g., restaurant/shampoo).

Overlap. To examine overlap in information flow networks, respondents were asked to identify the source of information for their piano tuner.

Other. Other measures included how long the senders and receivers had known each other, how long the

respondents had lived in the metropolitan area, how many piano teachers they had considered, the importance attached to selecting a good teacher, and the perceived risk in making a teacher selection.

Data Cross-checks Since we had to rely on subjects' verbal reports on

past behavior, several cross-checks on the data were performed.

Persons who had been named as a WOM source were asked whether or not they recalled telling anybody about the piano teacher and, if so, who it was (unaided recall). If the person who had identified the sender was not mentioned, the respondent was asked whether s/he re- membered telling the person about the service (aided recall).

Of the nonteacher sources that were contacted and asked to confirm the interaction, 45 percent recalled the interaction with no prompting (unaided) and 39 percent confirmed the conversation when asked if they recalled talking to the other person about lessons (aided recall). The remaining 16 percent of interactions could not be verified. A majority of these "failures" were with other music professionals (e.g., piano tuner, band director, choir director). These respondents noted that they are asked quite often for recommendations from individuals they hardly know and, therefore, do not re- member each referral. Others could not be verified due to refusals to participate or the fact that they were not asked for confirmation, usually because their name was mentioned as a source after they had already been in- terviewed, or they were cited by several respondents as a source and verification of each referral was not un- dertaken.

Respondents who were receivers of WOM information about one of the piano teachers were also asked how certain they were of the source(s) of that information. Ninety-five percent stated that they were either certain or very certain of the source.

Cross-checks were also performed on what senders and receivers said about each other for frequency of interaction, for importance of the relationship, and for how long they had known the other person. Correlations for senders and receivers were as follows: frequency of interaction = 0.78, importance of relationship = 0.69, and years known each other = 0.93. All were significant at p < 0.001. Overall, then, there are indications that the data were of sufficient quality to warrant the examination of the hypotheses.

RESULTS

Overall For the respondents who participated in both phases

of data collection, there were 130 sender-to-receiver WOM dyads on referral paths that were traced back to the teachers. The vast majority of these dyads involved


nonfamily members (85 percent). Since family dyads belonged to many different families, for analysis purposes they were treated as any of the other dyads rather than collapsing them into a single unit.

Most receivers reported that they had one sender (82 percent); 15 percent indicated two senders; two percent, three senders; and one percent, four senders. Most of the senders directly or indirectly linked to a piano teacher on referral paths informed one of the respondents (71 percent), 20 percent told two, six percent told three, and three percent informed five of the respondents. Thus, most of the respondents were senders or receivers only once. Although the majority of the respondents expressed that they considered selecting a good teacher as very important (84 percent), most of them considered only one teacher (62 percent). Nevertheless, the majority of respondents indicated low risk in their final decision (68 percent).

There were 73 referral paths originating with one of the teachers and leading to a final actor on a path. Of these paths, seven (10 percent) had one sender/receiver dyad, 38 (52 percent) had two dyads, 11 ( 1 5 percent) were composed of three dyads, seven (10 percent) had four dyads, nine (12 percent) consisted of five dyads, and one (one percent) had six dyads. It is noteworthy that 38 percent of the paths involved at least four different individuals.

The hypotheses are examined next. The results are summarized in Table 1. Representative case examples of referrals will be presented at times to enrich the statistical analysis (see Figure B).

Strength of Weak Ties Hypothesis 1. It was anticipated that weak ties would

be more likely than strong ties to serve as bridges through which WOM referrals flow. A prerequisite to testing this hypothesis as well as several of the others is the determination of strong and weak ties, subgroups, and bridges serving as conduits for the flow of information.

First, the receivers' data on the type of relation with the senders were dichotomized. If the sender was labeled a relative, friend, or neighbor, the tie was classified as "strong." If the sender was identified as merely an acquaintance or a neighbor but primarily an acquaintance, the tie was classified as "weak." Although it is acknowledged that an individual's social relations with others typically include a spectrum of ties ranging from strong to weak, this dichotomy results in a conservative test of our hypotheses. It is also consistent with oper- ationalization practices in this area (e.g., Lin, Dayton, and Greenwald 1983), but to provide a formal check on the dichotomy's validity, we also examined the frequency of contact and the importance attached to the relation across these two categories. Congruent with Granovetter's (1973) notions of tie strength, at the time of information acquisition behavior, strong ties inter-

TABLE 1

SUMMARY OF RESULTS

Hypotheses Results

1 Weak ties activated for a referral are Supported more likely than strong ties to serve as bridges through which WOM referrals flow.

2 When a consumer is in social Supported relations with both strong and weak ties who are available as potential sources of referral, strong ties are more likely than weak ties to be activated for the referral flow.

3 Active information seeking is more Not supported likely to occur from strong-tie than (opposite) weak-tie sources of referrals.

4 Information from strong-tie referral Supported sources is perceived as more influential in receivers' decision- making than is information obtained from weak-tie referral sources.

5 Consumers with joint membership in Supported a subgroup of referral actors for one good are more likely to prefer the same brand for other goods than are those consumers who belong to a different or to no subgroup.

6 Strong ties, who were activated for Supported the flow of referral for one good, are more likely than weak ties to be activated as sources for a related good.

7 Weak ties activated for the WOM Not supported referral flow of information are more heterophilous than activated strong ties.

8 Of an individual's potential personal Supported sources of information, the more homophilous the tie, the more likely it is activated for the flow of referral.

9 As homophily of a tie increases, Not supported information provided by an activated tie is perceived by receivers as more influential in decision-making.

acted more frequently than weak ties (X2 = 27.46, p < 0.001). For example, of 65 sender/receiver dyads in- teracting on a daily or weekly basis, 61 (94 percent) were in the strong-tie category. Further support was obtained when the ratings on importance attached to a tie were examined. The ties in the strong-tie classification were judged more_important by receivers than those grouped as weak (X = 3.46 and X = 1.23, respectively; t = 14.35, p < 0.001).

Second, more densely knit subgroups within the overall social structure of referral actors needed to be


FIGURE B

DIFFUSION OF INFORMATION AND GROUP STRUCTURE

NOTE: The who-told-whom network (directed lines) is embedded in the group structure

(nondirected lines) for one of the marketers (1 55). For illustrative purposes, not every group

and dyadic social relation is exhibited. Reading clockwise, the groups are 27, 146, 155; 8,

48, 145; 34, 36, 42, 155; 32, 118, 147, 155; 31, 51, 52; 30, 72, 155; 1, 60, 155; 60, 124,

155; and 22, 141, 148. Comembership in the same social system such as church (e.g., 8,

48, 145) or neighborhoo2 (e.g., 34, 36, 42, 155) facilitated the emergence of these subgroups.

determined. The sociological concept of group suggests that only the strong ties should be employed in its determination. However, not every strong tie is necessarily a relevant source of information. For example, if persons A and B were in a strong-tie social relation at the time of A's WOM behavior related to piano teachers, but B's information acquisition behavior occurred at a later point in time, B could not have been a potential source of information for A. Thus, only those strong ties were employed for subgroup determination that existed at the time of an actor's information acquisition behavior and that were his/her potential sources of information. The subgroups were found with an algorithm contained in Sonet-I (Foster and Seidman 1978). It searches for socially connected referral actors until no other actor can be added to a subgroup of at least three connected individuals. This algorithm was selected because it was substantively appropriate for the present study.

Third, the information flow paths were embedded in the resulting social structure to search for those WOM dyads that were not in subgroups. To qualify as a bridge, these dyads had to be the only interpersonal link between groups (Knoke and Kuklinski 1982).

Of 130 WtOh M dyads, only 23(18 percent) were in a weak-tie relation. Thus, the vast majority of ties activated for the flow of referral arose from stronger rather than weaker social relations. To test the hypothesis, however, it is necessary to compare the relative frequency of bridges across the categories of tie strength. Of the 23 weak-tie dyads of Wa OM, 22 percent (five

dyads) were bridges, as compared to six percent (seven dyads) of the 107 strong ties. The hypothesis is supported (Z = 2.29, p < 0.05).

One example of a weak tie bridging subgroups is the link between 51 and 118 (six o'clock position of Fig- ure B):

51/118: 51 's son was taking piano lessons from another teacher and needed more advanced instruc- tion. The previous piano teacher told 51 to call 1 18 who is also a piano teacher. However, 118 was not taking new students but recommended 155. Actors 118 and 155 belong to a group with actors 32 and 147. They call each other friends. These relations emerged from comembership in the same music teacher association. In turn, 51 passed information about 155 to 31 and 52, all of whom belong to the same church. Thus, the acquaintance tie between 51 and 118 served as a bridge linking two otherwise disconnected subgroups, thereby extending path length.

Strength of Strong Ties Hypothesis 2. According to this hypothesis, it was

expected that strong ties would be more likely than weak ties to be activated for the flow when both are available as potential sources of information. Most actors (90) had access to both strong-tie and weak-tie potential information sources. In support of the hypothesis, 27 percent (74/273) of the potential strong-tie sources were activated, as compared to seven percent (16/21 1) of the weak-tie ones (X2 = 17.32, p < 0.001). These data indicate also that only relatively few of relatively many potential personal sources of information were activated for information flow.

Hypothesis 3. This hypothesis predicted that information seeking would be more likely to occur from strong-tie sources of information. The results were in direct contrast to expectations. Eighty-six percent of the weak ties activated for the flow were solicited for information, compared to 50 percent of the strong ties (x2 = 8.14, p < 0.01).

The dyad 51/49 at the six o'clock position of Figure B provides an example of a weak tie that was solicited for information:

51/49: These individuals live in the same neighborhood, but they do not socialize or know each other well. They call each other acquaintances. Their children, however, sometimes play together and 49 knew that 5 I's son played piano. When 49's child wanted to start lessons, 49 called 51 to find out who her son's teacher was.

Although most senders in the present study were solicited for information (57 percent), it is noteworthy that the remaining referral occurrences "somehow" arose during conversation. Although no decisive evidence can be offered, it appears that situational or environmental cues prompted these WOM instances. One


TABLE 2

CONGRUENCY EFFECTS

Congruence Piano Restaurant Dentist Tuner Shampoo

Percent congruence within group 26 25 17 19 10 Percent congruence not in same group 16 9 2 6 3 Percent raw effect 10 16 15 13 7 Chi-square 3.43a 41.41b 240.64b 50.26b 16.21b

ap < 0.10. bp < 0.01.

example is 60/149 (a weak tie at the ten o'clock position of Figure B).

60/149: The children of these two individuals were taking swimming lessons. While 60 and 149 were waiting for their children, they started to talk about their children's activities, and 60 told 149 about 155.

Hypothesis 4. It was expected that information from strong-tie referral sources would be perceived as more influential than information obtained from weak-tie referral sources in receivers' decision-making. The WOM actors who were nonusers of the service (i.e., those who had not engaged in decision-making about the service provided by any of the three piano teachers) were omitted from the analysis, leaving data on 84 activated strong ties and 18 activated weak ties. The mean level of influence for the strong ties was 4.24, while the mean level of influence for weak ties was 3.56 (t = 2.22, p < 0.05), supporting the hypothesis.

With regard to our data on most/least influential sources, there were only five cases where an individual employed a strong as well as a weak tie as sources of referral. While a formal statistical test was therefore not performed, it is noteworthy that in four of the five instances, weak ties were always ranked as least influential.

The dyads 147/5 (4 o'clock position), 32/49 (5 o'clock position), and 8/48 (1 o'clock) provide examples for strong ties perceived as highly influential.

147/5: 5 originally knew 147 from working with her on a church music program. 5 also knew that 147 was a member of the state's music teacher association. 5 asked 147 to recommend a teacher. 5 felt she "could trust" 147's opinion, especially since 147 and 155 were friends.

32/49: 32 was teaching 49's daughter, but they lived "too far apart." 49 asked her neighbor 51 from whom her son was taking lessons. 51 recommended 155. 49 then asked 32 about 155 and she highly recommended 155. 49 "valued" 32's recommen- dation, since 32 is a piano teacher and, thus, is "knowledgeable in the music field."

8/48: 8 and 48 had been neighbors. 48 knew 8's daughter was taking lessons. 8 was very pleased with her daughter's progress and teacher. 48 felt the information obtained from 8 was very influential because 48 "knew nothing about the piano."

Hypothesis 5. It was expected that consumers with joint membership in a subgroup of referral actors for one good would be more likely to prefer the same brand for other goods than would those consumers who belong to a different or to no subgroup. Of the 107 strong ties activated for information flow, 81 (76 percent) belonged to subgroups as previously defined. Following the analysis format employed by Reingen et al. (1984), contin- gency tables were generated for the various products and services examined, with one dimension being "in the same subgroup/not in the same subgroup" and the other being "same brand preference/not the same brand preference." Chi-square tests for each product or service were then conducted.

The results are provided in Table 2. The findings for restaurant, dentist, tuner, and shampoo were all significant at p < 0.001, for piano at p < 0.10. The average raw effect (i.e., percent brand congruence for actors in the same subgroup minus percent brand congruence for actors not in the same subgroup) was 12.1 percent, and the range was from seven percent for shampoo to 16 percent for dentist. Overall, these findings support the hypothesis of greater brand congruency among subgroup members for the products and services examined in this study.

Hypothesis 6. This hypothesis predicted that strong ties that were activated for the flow of referral for one good would be more likely than weak ties to be activated for the flow for a related good. Of 31 individuals mentioned as sources of information for a piano tuner who were also members of the piano teacher networks, all were in a strong-tie relation with the receiver (X2 = 9.08, p < 0.01).

Homophily/Heterophily Hypothesis 7. This hypothesis predicted that weak

ties activated for the flow of referral would be more heterophilous than activated strong ties. Contrary to expectation, however, there was no significant relationship between strong/weak ties activated for referrals and homophily/heterophily (X2 = 0. 10, p > 0. 10).

Hypothesis 8. It was expected that the more homophilous the tie, the more likely it would be activated from the set of potential sources of information. Of the


activated ties, 37 percent were homophilous, compared to 22 percent of the nonactivated ties. The hypothesis is supported (X2 = 8.93, p < 0.01).

Hypothesis 9. According to the ninth hypothesis, it was predicted that information provided by an activated tie would be perceived as more influential in decision- making as the homophily of the tie increases. To test this hypothesis, simple regression analysis was performed. Perceived influence of the source was the de- pendent variable, and the independent variable was the dummy-coded homophily/heterophily. Individuals who had not engaged in decision-making about the service provided by any of the three teachers (i.e., nonusers) were ignored in this analysis. The hypothesis did not receive confirmation (F = 0.64, p > 0.10).

DISCUSSION

This study demonstrates the different roles played by weak and strong social ties in macro-level and micro- level WOM phenomena.

Strength of Weak Ties

The special significance of weak ties was found to be their disproportionately greater frequency to be bridges that allowed information to travel from one distinct subgroup composed of referral actors to another in the broader social system. Thus, the present study extends Granovetter's (1973; 1982) claim that weak ties create bridges by providing empirical evidence that these bridges are indeed activated as intergroup channels of information. By examining the function performed by weak ties in the transmission of referrals between subgroups, we have demonstrated that one relational property-strength of tie-can provide a useful explanation of how dyadic interactions among consumers aggregate to form large-scale patterns. This is potentially important in addressing a variety of topics of interest to scholars of consumer behavior such as the diffusion of fashions, innovations, and rumors about products as well as the formation of widely shared consumer attitudes.

Strength of Strong Ties

Whereas weak ties were found to play a crucial role in the flow of WOM information across groups, strong ties were shown to be important at the micro level of referral behavior. When both strong and weak ties were available as sources of information, strong ties were more likely than weak ties to be activated for the flow of information. The greater frequency of social contact among strong-tie individuals probably accounts for this finding. This argument may also explain the unexpected result that strong ties were less likely to be directly solicited for information than weak ties. Consistent with

Belk's (1971) observations, it appears that many of the strong-tie referral instances were induced by situational or environmental cues when the topic of piano lessons or teacher "somehow" arose during a conversation initiated for other reasons. The likelihood of more inci- dental WOM communication may be enhanced as communication frequency increases. However, an implication of the present findings is that Belk's (1971) notion of this "casual" WOM may not be generalizable to weak ties, the vast majority of which were actively solicited for information in the current study.

Strong ties activated for the flow of information were also perceived by receivers as more influential than weak ties in decision-making. Consistent with the results obtained by Weimann (1983), an important implication of this finding is that the bridging function of weak ties is more conducive to the flow of information, whereas strong ties are more crucial to the flow of influence. This may be explained by source credibility. It is likely that a strong tie may be perceived as a more credible source of information than a weak tie. However, since source credibility was not assessed by the study, no decisive evidence can be offered at this time.

Strong ties were not only perceived as more influential, but they were also far more numerous as sources of information than weak ties. This is in contrast to several previous studies (e.g., Granovetter 1974) that found weak ties to dominate the flow of information. The inconsistency may be explained by information availability. In the present study, information was most often available from strong-tie sources. Thus, there was usually no need to activate ties beyond those available in the consumers' own social circles.

Finally, since the vast majority of strong ties were in groups composed of potential sources of information, strong ties may enable an individual consumer to have direct access to an enriched information environment. Noteworthy in this context are the study's findings that the overlap in personal sources of information for related services was solely accounted for by strong ties, and that there was greater brand congruency among subgroup members for a variety of products and services. The latter finding is especially significant because the subgroups in the present study were generated on the basis of only one type of event or activity (referral behavior involved in the selection of a service).

Homophily/Heterophily

Whereas the predictions derived from tie strength were usually confirmed, those stemming from homophily received less support. A noteworthy exception is that tie activation was found to be positively related to homophily. This is important because the present study extended previous analyses by comparing the ties that were activated against those that were not activated for the flow of information. The other hypotheses positing positive relationships between homophily and tie strength as well as perceived influence did not receive


confirmation, but the possibility of imprecise measurement should not be ignored. As has traditionally been the case, demographic measures were employed in the testing of the homophily hypotheses. Future research may benefit from incorporating into the analysis atti- tudinal/lifestyle measures of homophily and from examining effects of degrees of homophily on WOM behavior.

Limitations of the Study These findings are subject to several limitations. The

research focused on who-told-whom processes related to one service that was not formally promoted by its marketers. On the one hand, this setting suited well the aims of the study and facilitated the testing of its hypotheses. On the other, it is unknown whether the findings can be generalized to formally promoted products and services or to other facets of informal communications such as negative WOM, feedback loops, and information exchange behavior among consumers. Al- though different settings will likely produce variations in network structure (e.g., with regard to the number and length of paths, connectedness, etc.), it is not obvious why they would produce strikingly different findings as they relate to the impact of relational properties on WOM communication. The latter was the focus of the study, as opposed to an internal analysis of more setting-specific network features. Nevertheless, more research is clearly needed, replicating and extending the present analysis.

With regard to methodology, a limitation is that several WOM paths could not be completed due to non- response or incomplete retrieval of WOM instances from memory. Although the study does not appear to suffer unduly from these problems, some bias may have entered the analysis. The study also relied on individuals' verbal reports on past behavior. Cross-checks performed on the data suggest a high level of confirmation of the verbal reports. However, there was no true criterion against which the reports could be compared.

Future Research Directions Three major suggestions are made regarding future

research in addition to the ones mentioned earlier. First, although the relational perspective that guided

the present study is promising, it alone is unlikely to yield complete understandings of social phenomena such as WOM. It is, therefore, suggested to complement relational measures with attribute-based data. For example, the traditional communication variable of source credibility is a promising candidate for complementing the relational analysis of WOM behavior.

Second, there is a strong need for combining the network analysis of WOM behavior with an analysis at the level of the individual actor. The individual consumer has almost exclusively been the unit of analysis in recent consumer behavior research. Dyadic or group processes

are relatively underresearched (Rudd and Kohout 1983). The network approach stresses the latter, but complementing it with an analysis at the level of the individual consumer would enhance the present understanding of several important issues, including how WOM interaction precipitating out of social networks has an impact on attitude formation or change and how consumers' decision-making behavior both affects and is affected by properties of network structure. The relationship between social structure and influence especially needs to be more broadly examined than in the present study by including more complex measurement of the influence construct at the individual level and by expanding the boundary of a network to include actors in addition to those involved in referral activity. This calls for future research with a focus on obtaining an in-depth understanding of WOM actors' social mi- lieux, applying tools characteristic of the "social world" rather than the "structural" tradition of network analysis (e.g., McCallister and Fischer 1983).

Third, an enhanced understanding of social influence processes in consumer behavior may simply be obtained by examining which products or services consumers are more likely to "talk about." Consistent with the results obtained by Reingen et al. (1984), the current study highlights the importance of verbal communication arising from social relationships rather than the traditional notion of conspicuousness which has been so prominent in guiding the research on influences from others on a consumer's attitudes and behaviors (e.g., Bearden and Etzel 1982). Since the consumption of piano teaching and tuning services is probably more "private" than "public," the extensive (likely informational or expert) influence observed in the present investigation is probably due to factors other than conspicuousness.

CONCLUSIONS In summary, the study addressed several aspects of

WOM behavior that had not been examined in previous work. These were investigated from a relational perspective in a natural environment. Although the study has limitations, the initial findings are promising. Nevertheless, it is clear that a great deal of additional research remains to obtain a more satisfactory understanding of WOM phenomena. Especially needed is research that complements relational analysis with more traditional attribute-based approaches, relates the analysis at the level of the network to one at the individual level, and examines the cues prompting WOM behavior.

[Received March 1986. Revised December 1986.]

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Social Ties and WOM Referrals Behaviour

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