Page 250 - Becoming Metric Wise

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Indicators

Finally overall affinity is defined as:
D 1 E
(7.30)
D 1 E 1 F
It is the ratio of citations from journals in J’s field over the total num-
ber of received citations.
The self-cited rate expresses the degree of narcissism of the journal (in
terms of citations). If it is equal to one, all received citations come from
the journal itself. This is an extreme case of narcissism. If it is zero, all
citations come from other journals: it is the other extreme.
Own field affinity is zero if among all citations received from the jour-
nal’s own field, none comes from other journals in the field. It is one if
all field citations come from other journals in the field.
Again, instead of a journal one may use these indicators for an author
or a group of authors; and instead of a field one may use a country, an
institute, a language, and so forth.

7.13.3 Synchronous Impact Factors in So’s Framework

Finally So (1990) also proposes the following synchronous impact factors,
constructed via partial indicators D, E, F, and G. Again a fixed publication
window is used. Partial indicators D, E, and F are already defined in
Subsection 7.13.2. G is the number of articles published during the fixed
publication window.
Self-directed impact, i.e., the self-cited rate, is defined as:

D
(7.31)
G
Own-field impact is defined as
D 1 E
(7.32)
G
Other-field impact is defined as:
F
(7.33)
G
Finally, overall synchronous impact is defined as:
D 1 E 1 F
(7.34)
G