Page 231 - Becoming Metric Wise

222 Becoming Metric-Wise

should not be seen as an element in a research evaluation, but rather as an
element in the (historic) study of authors’ careers and the response to
their publications by colleagues.
According to Pan and Fortunato the SAIF has the following
advantages:
• The SAIF is a dynamic index, showing the ups and downs in a
person’s career.
• The SAIF is an average so it is high if most papers published during
the publication window are well cited, whereas low quality work (or
not yet recognized work) keeps the score down. For this reason using
the SAIF may be an incentive to focus on quality (or popularity?)
instead of quantity.
• The SAIF is easy to calculate.
To this list we can add the following advantage: As the SAIF is an
average, it may be influenced by one exceptionally highly cited publica-
tion. Yet, in this type of application this is an advantage as one wants to
recognize this type of work.
At the same time, the SAIF also has some disadvantages:
• It makes no sense to calculate an SAIF for persons who rarely publish.
• Work published in a source outside the set covered by the used
database has no influence on the SAIF (or any other general impact
factor), while such work may have contributed to a Nobel Prize.
Another type of impact factor is the Web Impact Factor (WIF),
introduced by Ingwersen (1998). The WIF of a web site or group of
related websites such as all those with domain .dk (Denmark) is defined
as the sum of the number of external inlinking pages plus the number
of self-link web pages, divided by the number of web pages. External
inlinking pages are webpages external to a given site (in the example: all
those which do not carry the domain name .dk) which point at least
once to that set of sites, e.g., a site with domain name .dk. Self-link
web pages are websites which point at least once to the set of sites
to which they themselves belong. The denominator consists of the
number of websites (not the number of links) of the set under investiga-
tion. Although a clever idea it has turned out that it is almost impossi-
ble to determine the three numbers needed for its calculation. This
explains why, after a short period of enthusiasm, use of the WIF is
nowadays almost abandoned. Yet, total number of external inlinks plays
a role in determining the Webometrics Ranking of World Universities
(see Subsection 8.4.3).