Page 164 - Becoming Metric Wise

156 Becoming Metric-Wise

Table 6.1 A complete p-c matrix of a hypothetical journal
Year of publication 1 1 2 2 2 3 3 3 4 4 4 4
Articles A B C D E F G H I J K L
Number of citations received in year 1 1 0
Number of citations received in year 2 4 2 2 1 1
Number of citations received in year 3 6 2 1 4 6 3 0 0
Number of citations received in year 4 8 1 0 5 9 3 1 2 4 1 2 3

citations in the short term.” In this way, well-known (5heavily cited)
scientists publish mainly and preferably in well-known (5heavily cited)
journals.
The best known—and most criticized—criterion for a journal’s visibility
is the journal impact factor (JIF). This indicator and related ones are dis-
cussed in this chapter. Note that here we consider the JIF as the result of a
specific mathematical formula. At this point we do not go into details about
the way databases such as the Web of Science (WoS) apply this formula.

6.2 THE PUBLICATION-CITATION MATRIX PER ARTICLE

6.2.1 A Complete Publication-Citation Matrix
A complete publication-citation matrix (in short, p-c matrix) of a journal
contains all citation information for each of its articles. Table 6.1 provides
an example in which we consider a fictitious journal publishing, for sim-
plicity’s sake, very few articles. We note that all citations come from a
given pool of citing articles (Ingwersen et al., 2001).
The numbers in Table 6.1 mean the following: the number 6 in the
column starting with 2E, means that article E, published in year 2,
received 6 citations in year 3.

6.3 THE PUBLICATION-CITATION MATRIX OF A JOURNAL
AND THE GARFIELD-SHER (1963) IMPACT FACTOR:
INTRODUCTION

When one is interested in knowing a journal’s impact factor, the number
of citations received by each individual article plays no role: all articles
published in a particular year are brought together. For this purpose
Table 6.1 is replaced by Table 6.2. This type of table contains all data
needed to calculate impact factors (see further).