Page 248 - Becoming Metric Wise

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Indicators

window. Fields are assumed to be disjoint: no article or journal belongs
to two or more fields.
A is the number of references (not necessarily different ones) in
journal J in year Y to articles published during the publication window in
this journal (J).
B is the number of references in journal J in year Y to articles pub-
lished, again during the publication window, in other journals, but in the
same field as journal J.
C is the number of references in journal J in year Y to articles pub-
lished during the publication window, in journals not belonging to J’s
field.
Hence A 1 B 1 C is the total number of references in journal J in
year Y to publications from the publication window.
The first index is the journal’s self-citing rate in the year Y for a given
publication window. It is defined as:
A
(7.23)
A 1 B 1 C
Own-field openness is defined as
B
(7.24)
A 1 B
It is the ratio of references to other journals in the field over the num-
ber of references to all journals in the field (including the journal J itself).
Other-field openness is defined as:
C
(7.25)
A 1 B 1 C
It is the ratio of references to journals not in J’s field over the number
of references to all journals.
Finally overall openness is defined as:

A 1 B
(7.26)
A 1 B 1 C
It is the ratio of references to journals in J’s field over the number of
references to all journals.
The self-citing rate expresses the degree of closeness of the journal to
external input. If it is equal to one, all citations come from the journal
itself. This is an extreme case of closeness. If it is zero, all citations come
from other journals: it is an extreme case of openness.