Abstract
Although the 2-year Thomson-Reuters Impact
Factor (IF) has become a usual tool for measuring
the scientific productivity of all fields of the natural
sciences, its behavior in
the particular case of the journals of pure
mathematics (the area MATHEMATICS in the
thematic directory of Thomson-Reuters) is far from
being stable when its values in consecutive years
are considered. If we consider the changes of the
values of the IF of a given journal in the last
decade, it can be easily seen that the variation of the
values is surprisingly high if we compare with other
disciplines. Mathematical journals seem to have the
worst behavior regarding the time stability both of
the IF and the position in the IF list.