An Assessment of Research-Doctorate Programs in the United States Engineering (1982) / Chapter Skim
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Appendix F: Data on Publication Records (Measures 15 and 16)
Appendix F: Data on Publication Records (Measures 15 and 16)
Pages 170-187
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From page 170... ...
The following pages have been excerpted from Chapters VI and VII of this report and describe operational considerations in compiling the publication records included here (measure 15) and the methodology used in determining the "influence" of published articles (measure 16)
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From page 171... ...
Later sections of the chapter consider publication and citation count parameters in further detail, including discussions of data bases, of field-dependent characteristics of the literature, and of some cautions and hazards in performing citation analyses for individual scientists. The basic stages which must be kept in mind when doing a publication or citation analysis are briefly summarized in Figure 6-1.
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From page 173... ...
Since most abstracting and indexing sources have been expanding their coverage over time, any publication count covering more than a few years must give careful consideration to changes in coverage. Furthermore, the timeliness of the secondary sources varies widely, with sources dependent on outside abstracters lagging months or even years behind.
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From page 174... ...
Multiple authorship problems arise less often in institutional publication counts since there are seldom more than one or two institutions involved in one publication. A particularly vexing aspect of multiple authorship is the first author citation problem: almost all citations are to the first author in a multi-authored publication.
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From page 175... ...
Although the publisher of the Science Citation Index, the Institute for Scientific Information, tries to maintain a consistent policy in attributing institutional affiliations, when authors have multiple affiliations the number of possible variants is large. In the SCI data base on magnetic tape, sufficient information is included to assign a publication with authors from a number of different institutions in a reasonably, fair way to those institutions; however, in the printed Corporate Index, one has to refer to the Source Index to find the actual number of authors, or to the paper itself to find the affiliations of each of the authors.
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From page 176... ...
In a Computer Horizons study completed in 1973 the amount of agency support acknowledgement was tabulated in twenty major journals from five different fields.4 Table 6-1 summarizes those support acknowledgements for 1969 and 1972. In 1969, only 67% of the articles in 20 major journals acknowledged financial support.
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From page 177... ...
177 0 a, 0 ~4 a, A: ~4 al U)
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From page 178... ...
A classification of papers at the journal level has been used in the influence methodology discussed in Chapters VII through X Citation Counts Citation counts are a tool in evaluative bibliometrics second in importance only to the counting and classification of publications.
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From page 179... ...
Some of the characteristics of the literature which are revealed by citation analysis are noted on Figure 6-1. These characteristics include: The dispersion of references: a measure of scientific "hardness", since in fields that are structured and have a central core of accepted knowledge, literature references tend to be quite concentrated.
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From page 180... ...
The journal "impact factor" introduced by Garfield is a size-independent measure, since it is defined as the ratio of the number of citations the journal receives to the number of publications in a specified earlier time period, 1 This 1Eugene Garfield, "Citation Analysis As a Tool in Journal Evaluation " Science 178 (November 3, 1972)
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From page 181... ...
The idea of counting a reference from a more prestigious journal more heavily has also been suggested by Kochen.2 A third limitation is that there is no normalization for the different referencing characteristics of different segments of the literature: a citation received by a biochemistry journal, in a field noted for its large numbers of references and short citation times, may be quite different in value from a citation in astronomy, where the overall citation density is much lower and the citation time lag much longer. In this section three related influence measures are developed, each of which measures one aspect of a journal's influence,with explicit recognition of the size factor.
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From page 182... ...
A citation matrix for a specific time lag may also be formulated. This would link publications in one time period with publications in some specified earlier time period.
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From page 183... ...
The denominator of this expression is the row sum n Si = `7 ~ Cij j=1 corresponding to the ith unit of the citation matrix; it may be thought of as the "target size" which this unit presents to the referencing world. The influence weight, Wi, of the ith unit is defined as n 'I Wi = ~7 ~ k=1 Wk Cki si In the sum, the number of cites to the ith unit from the kth unit is weighted by the weight of kth (referencing)
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From page 184... ...
With the choice of target size Si, the value | = 1 is in fact an eigenvalue so that Equation 1 itself does possess a solution. `,T Using the notation ~ for the transpose of IT ~ ~ ik Ski defined by ; introducing the Kronecker delta symbol (1 i = k ilk tO i ~ k the equation can then be written
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From page 185... ...
The normalization or scale factor is then fixed by the condition that the size-weighted average of the weights is 1, or
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From page 186... ...
Each root of the characteristic equation determines a solution vector or eigenvector of the equation, but the weight vector being sought is the eigenvector corresponding to the largest eigenvalue. This can be seen from the consideration of an alternative procedure for solving the system of equations, a procedure which also leads to the algorithm of choice.
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From page 187... ...
C i = ~ w(m x Ski ~ ( ) k=1 i k=1 j=1 ji The exact weights are therefore Wi = Wi ~ ~ ~ )
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