By Justin Dubé
Given that sex tends to be a private activity, we often rely on the “honour system” when conducting sex research: we ask people to self-report aspects of their sexual lives and trust them to be honest. This is one reason why sex researchers strive (and struggle!) to reconcile differences in the number of opposite-sex partners reported by men and women. Within a specific timeframe and location, the average number of opposite sex-partners should be the same between genders. Yet, across the globe, men report twice as many opposite sex partners as women. So, what gives?! Are people lying? Is sex research doomed? Should I go back to a career in music?!
In an effort to answer these questions (and keep my music career on hiatus, presumably), Mitchell et al.  tested whether the following factors account for why men report more sexual partners than women:
- Men use sex workers more often than women and sex workers are underrepresented in research
- Casual sex is more socially acceptable for men relative to women
- Men estimate and women count their number of lifetime sexual partners
What did they do?
Mitchell et al.  asked 6023 men and 7170 women to report the number of opposite-sex individuals that they had vaginal, oral, or anal sex with over the following three time points: past year, past five years, and lifetime. Participants also reported on the number of opposite-sex partners they paid to have sex with, their sexual attitudes, and whether they estimated or counted their number of sexual partners.
What did they find?
Men were more likely to have paid for sex than women; yet, women were more likely than men to exclude paid sex-partners from their total number of partners. Men were also more likely to report extreme values in their number of lifetime sexual partners than women (e.g., at the 99th percentile, this value was 110 for men versus 50 for women).
For social approval, women were more likely to endorse more conservative sexual attitudes than men (e.g., women were more likely to disapprove of casual sex and one-night stands).
Regarding gender differences in how people generated their numbers, men were more likely to estimate their lifetime number of opposite-sex partners than women (who relied more on counting versus estimation). In both genders, counting and estimating were linked with lower and higher numbers of sexual partners, respectively.
When these differences were accounted for, the gap between men and women in their number of lifetime sexual partners was reduced from 7 to just under 3.
What does it mean?
Men report more opposite-sex partners over the course of their lives than women; however, this gap is significantly reduced when differences in counting strategies and sexual attitudes are accounted for. Although the current study included sexual minority individuals, an examination of gender differences in same-sex partners not conducted. Nevertheless, findings suggest sex researchers can improve the accuracy of their data if they encourage participants to count rather than estimate values, exclude or verify extreme reports, and account for sexual attitudes. In sum, the current findings suggest that my guitar will remain perched on its stand for a few more years.
 Mitchell, K. R., Mercer, C. H., Prah, P., Clifton, S., Tanton, C., Wellings, K., & Copas, A. (2019). Why do men report more opposite-sex sexual partners than women? Analysis of the gender discrepancy in a British national probability survey. The Journal of Sex Research, 56(1), 1-8.