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Indicators

value (many publications AND many citations 5 high impact). Much
more h-type indicators have been introduced for which we refer the
reader to the following reviews Alonso et al. (2009) and Egghe (2010c).
Generally, one may say that only the h-index and the g-index are often
applied.

7.7 A GENERAL IMPACT FACTOR

The term impact factor refers to a set of indicators originally introduced
for journals as illustrated in the previous chapter. Yet, it is clear that these
indicators can, at least theoretically, be applied to any set of articles if the
data are of the required format. By this we mean that one needs at least
one row in the citation part of the p-c matrix in order to calculate a
synchronous impact factor, and at least one column for calculating a
diachronous one.
One such set is the set of all articles (co-)authored by one scientist.
Let us hasten to say that for scientists who do not publish many articles
calculating any impact factor is utterly meaningless. Yet for very active
researchers it might be of some interest to calculate author impact factors.
Pan and Fortunato (2014) propose a 5-year synchronous author impact
factor (SAIF). They show that this SAIF is capable to capture trends and
variations in the impact of the scientific output of a researcher.
Concretely the SAIF of a scholar in the year Y is defined as:

P 5
i51 CITðY; Y 2 iÞ
5
SAIFðYÞ 5 P (7.13)
i51 PUBðY 2 iÞ
Here PUB(Y 2 i) denotes the number of publications coauthored by
this scholar in the year Y 2 i, and CIT(Y,Y 2 i) denotes the number of
citations of articles published in the year Y 2 i received in the year Y.
Recall that publications and citations are those included in a chosen data-
base such as WoS or Scopus. We note that Pan and Fortunato were
certainly not the first to have the idea to apply the impact factor
construction to a single author although we were not able to find the
originator of this idea. However, they seem to be the first to study its
behavior for a number of individuals (Nobel Prize winners) and this over
a long period of time. They prove that, indeed, the SAIF is capable of
showing the highlights in their career. The use of an author impact factor