Honesty

Women don’t always answer surveys honestly, but give answers they believe are expected of them. 

“Women are sensitive to social expectations for their sexual behavior and may be less than totally honest when asked about their behavior in some survey conditions,”In this study, the researchers asked men and women about their sexual attitudes and behaviors under several different testing conditions – including one in which the participants believed they were connected to a lie detector machine.Women’s answers were closer to men’s in some areas of sexual behavior when they thought lies could be detected. Men’s answers didn’t change as much as did women’s under different testing conditions.

http://researchnews.osu.edu/archive/sexsurv.htm