Page 126 - Becoming Metric Wise

117
Publication and Citation Analysis

the fact that the ego leads the citation identity list. Self-citations refer to a
more recent group of publications than other citations do. This recentness
of author self-authors might indicate the high degree of continuity in the
work of individual scientists. One of the important findings of
Tagliacozzo is that self-citations are more often repeated in the same arti-
cle than other citations. If we assume that repetition of the same reference
in the text of an article is an indication of the significance of the cited
work for the citing work then the set of self-citations clearly stands out as
having a particular prominence among the other references. Contrary to
expectation, the results of the study showed no significant relationship
between the size of the bibliography and the extent of self-citing. There
was, moreover, also no significant relationship between the amount of
self-citing and the productivity of the author.
Lawani (1982) distinguishes two genera of author self-citations: syn-
chronous and diachronous self-citations. An author’s synchronous self-
citations are those contained in the references the author gives (those
studied by Tagliacozzo; self-citations on article level which are not on
author level do not play any role here), whereas diachronous self-citations
are those included in the citations an author receives (and these include
self-citations on article level). The synchronous self-citation rate, or bet-
ter, the self-citing rate of an author over a given period is the ratio of this
author’s self-citations divided by the number of references given during
this period. Note that these references (to oneself or to others) do not
need to be different, and usually are not. The diachronous self-citation
rate, or better, the self-cited rate of an author over a given period is the
ratio of this author’s self-citations divided by the total number of received
citations during this period. For example, if an author writes a paper
with 20 references, 4 of which refer to the author’s own work, then the
self-citing rate is 4/20 5 0.2. If he receives during one month 30
citations, 10 of which originate from his own work, then the self-cited
rate is 10/30 0.33.
Besides an author’s self-citing and self-cited rate on may also define
and study a research group’s, a journal’s or a country’s self-citing and self-
cited rate.
Lawani (1982) indicates the practical implications of high or low self-
citing and self-cited rates. High self-cited rates may be an indication of
poor research (the author is mainly cited by himself). On a more positive
note, White (2001) writes that a high self-cited rate may indicate intellec-
tual isolation. Moreover, a researcher’s self-citing rate may be high, but if