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194 Becoming Metric-Wise

6.19 THE MEDIAN IMPACT FACTOR

A group of colleagues from Thailand proposed a new kind of impact fac-
tor, the cited half-life impact factor, or better median impact factor, in
short MIF (Rousseau, 2005a; Sombatsompop et al., 2004). In this
approach the actual form of the journal citation curve is taken into
account, making this impact factor better suited for a comparison of
impact among fields and subfields. It is defined as follows:

TOT J ðYÞ=2
MIF J ðYÞ 5 (6.20)
CPUB J ðY 2 X; YÞ
In this formula, TOTJ(Y) denotes the total number of citations
received by journal J in the year Y; CPUB(Y 2 X,Y) denotes the cumula-
tive number of publications in the journal J, during the period [Y 2 X,Y],
where X denotes the median cited age (see Subsection 6.13.2). As citations
are collected in the same year (Y) this is a synchronous impact factor.
An example: the MIF(2003) for the journal Scientometrics.
The total number of citations received by the journal Scientometrics in
the year 2013 was 5129. Hence TOT 5 5129 and thus TOT/2 5 2564.5.
Further data can be found in Table 6.15. For simplicity we used as num-
ber of publications the number of so-called citable items according to
the WoS.
The median is attained somewhere between the 6th and the 7th year.
The cumulative number of citations received by articles published during

Table 6.15 Data for the calculation of Scientometrics MIF(2013)
Year 2007 2008 2009 2010 2011 2012 2013
# publications 129 128 189 226 217 254 255
Cumulative number of 1398 1269 1141 952 726 509 255
publications (going back
to the past)
Number of citations received 305 307 382 566 558 513 84
in the year 2013
Cumulative number of citations 2715 2410 2103 1721 1155 597 84
(going back to the past)
Cumulative percent of citations 52.93 46.99 41.00 33.55 22.52 11.64 1.64
(going back to the past)
Source: Taken from (Rousseau, 2005a).