Page 166 - Becoming Metric Wise

158 Becoming Metric-Wise

6.4 SYNCHRONOUS IMPACT FACTORS
6.4.1 Definition of the Journal Impact Factor
Next we consider a larger p-c matrix, based on (Frandsen & Rousseau,
2005).
Table 6.3 is structured in the same way as Table 6.2. We see, for
instance, that this journal received in the year 2011 20 citations for arti-
cles published in the year 2009. In 2015 it received 6 citations to articles
published in that same year (2015).
The Garfield-Sher impact factor of this journal for the year 2013 is:

13 1 25
JIF ð2013Þ 5 5 0:691 (6.1)
2
30 1 25
In general, the Garfield-Sher JIF 2 for the year Y is defined as:

CITðY; Y 2 1Þ 1 CITðY; Y 2 2Þ
JIF ðYÞ 5 (6.2)
2
PUBðY 2 1Þ 1 PUBðY 2 2Þ
The symbol CIT(Y,X)informula (6.2) refers to the number of citations
received in the year Y by articles published in the year X.Itisassumed that
the pool of citing journals is known and that it is also clear about which
journal J one is talking. Otherwise one may write CIT J (Y,X). Similarly,

Table 6.3 A fictitious publication-citation matrix
Year 2009 2010 2011 2012 2013 2014 2015 2016
# publications 15 20 25 30 35 35 40 40
# citations received in the 10
year 2009
# citations received in the 15 10
year 2010
# citations received in the 20 14 10
year 2011
# citations received in the 30 20 14 8
year 2012
# citations received in the 25 25 25 13 8
year 2013
# citations received in the 20 22 30 20 12 8
year 2014
# citations received in the 17 18 25 26 18 11 6
year 2015
# citations received in the 15 16 20 22 25 17 10 6
year 2016