LIS618 lecture 6

Thomas Krichel

2002-10-26

Structure of talk

• course evaluations• OCLC firstsearch• citation indexing and searching• scirus

citation indexing

• is a technique that can be used if there on documents that cite other documents– scientific papers– patents– legal documents

• pioneered by Shepherd's citation index to case law since 1870s

citation vs word indexing

• word indexing as severe limitations– different authors use different words– language evolves, e.g. euphenics– controlled vocabularies can help but

• reduce the subject to the categories• are subject to human error

• in contrast citation indexing appears more mechanical and thus objective

citation quality

• good citation data is a sign of good scholarship

• good citation data– has all relevant papers cited to show that the

authors are aware of related literature– citation has to conform to journal style

• but citation styles vary a lot for disciplines• citations in the hard sciences are a lot

more formal

citation indexes to scientific papers

• essentially pioneered by Eugene Garfield

• chemical citation index in the late 50s

• index of genetics in the early 60s

• ISI issued an interdisciplinary science citation index in the 60s

• Extended to social science citation index and arts and humanities citation index

• virtual monopoly

what sources to index

• Bradford's law would imply that it takes 500 to 1000 journals to cover the literature that is essential to a discipline

• Garfield's law of concentration says that the tail end of one discipline is core in another discipline.

• In SCI, mid 70s data– 50% of all citations are in 250 journals– 75% of all citations are in 1000 journals– 84% of all citations are in 2000 journals

impact factor

• is the rate of citations that articles in a journal receive divided by the number of articles that a journal publisher

• has become over time a crucial indicator of journal quality

• given the ISI a monopoly position in the evaluation of journal quality

citation index for a year

NAIR KG66 BIOCHEMESTRY 5 150

DESOUSA RC J PHYSL PAR R 71 5 75

MASLINSK. C AGENT ACTION 5 183 75

…

68 CIRCULATION RESEARCH 23ANVERSA P LAB INV 33 125 75

…

Source index

LUTZ H

RETTENMA.G (DE) ULTRASONIC DIAGNOSIS OF RENAL DESEASE

DEUT MED WO 98 361 73 17RN8

• there is also a patent index

type of searches

• citation verification – uses source index only

• eponymic search• methodology search• follow-up searches• review searches• precise question searches• exhaustive bibliographies

usefulness of citation indexing

• subject categorization is – more precise – more stable– more flexible– more detailed

• reveals links between old and new papers

• draws our attention to events that have happened

most successful application

• google uses graph structure of web links to distinguish between important and not important pages.

• pages that have many links to them by important pages are deemed to be important.