# KS test for bimodal and unimodal distribution?

I am quite new to statistical tests and not sure how to exactly describe my question. I searched but could not find similar questions. Please do let me know if this is a redundant question. Thank you!

I recently tried to compare a distribution between male and female. Two-sample KS test seems to be a good fit and the result is somewhat strange to me. The distributions are shown in the following graph.

It is quite obvious that there are two modes in female's distribution, whereas only one exists in male's. The two sample KS test gives me somewhat weird result:

Two-sample Kolmogorov-Smirnov test

data:  male and female
D = 0.10714, p-value = 0.9834
alternative hypothesis: two-sided


The large p-value indicates insufficient evidence to reject the null hypothesis that they come from the same probability distribution, right? I think one of the reason is that my sample size is very low: (20+ for male and 50+ for female). But it is still too big -- whereas the empirical distributions are bimodal and unimodal.

Is there other more appropriate tests that I should use for these samples? Thank you so much!

• Thank you for the clarification. I should know that KS actually measure the biggest distance... But I still do not get your point on an artifact of the density estimate using too small a bandwidth. I think it still seems to be bimodal even if I changed the binwidth. Can you help me understand this? Thanks! – Zhiya Apr 19 '17 at 20:47