  The literature on gender differences in research performance seems to suggest
a gap between men and women, where the former outperform the latter. Whether
one agrees with the different factors proposed to explain the phenomenon, it is
worthwhile to verify if comparing the performance within each gender, rather
than without distinction, gives significantly different ranking lists. If there
were some structural factor that determined a penalty in performance of female
researchers compared to their male peers, then under conditions of equal
capacities of men and women, any comparative evaluations of individual
performance that fail to account for gender differences would lead to
distortion of the judgments in favor of men. In this work we measure the extent
of differences in rank between the two methods of comparing performance in each
field of the hard sciences: for professors in the Italian university system, we
compare the distributions of research performance for men and women and
subsequently the ranking lists with and without distinction by gender. The
results are of interest for the optimization of efficient selection in
formulation of recruitment, career advancement and incentive schemes.
