THE DISPARITY BETWEEN the number of sexual partners reported by men and women can largely be explained by a tendency in men to report extreme numbers and estimate rather than count their total, according to a new study.

The research, published in the Journal of Sex Research, found that together with gender differences in attitudes towards casual sex, this explains the gender gap found in many sex surveys.

Dr Kirstin Mitchell of the University of Glasgow and colleagues analysed the responses of over 15,000 men and women aged between 16 and 74 in the third National Survey of Sexual Attitudes.

The study sought to better understand why men always report more opposite sex partners on average than women, even though the average number should be about the same. Men in the survey reported an average of 14 partners over their lifetime while women reported seven.

Individuals who reported very high numbers of partners naturally skewed the average and this effect was stronger for men than for women. Men and women at the top end reported 110 and 50 or more partners respectively. Excluding these men and women reduced the overall average and began to close the gender gap.

The gap was further reduced when the participants’ accounting strategy was taken into consideration. Men were more likely than women to estimate rather than count sexual partners. For example, among those reporting between five and nine partners, 24% of men estimated compared with 15% of women.

According to the research, sexual attitudes also had an impact on reporting, with women generally being more conservative in their attitudes than men. They were less likely to view one-night stands as ‘not wrong at all’ (9% versus 18%) and more likely to view a married person having sex with someone other than their partner as ‘always wrong’ (65% versus 57%). Adjusting figures to take these attitudes into account narrowed the gender gap even further.

Dr Mitchell said accurate reporting of sexual partners is crucial for many reasons, including assessing individual risk of sexually transmitted infections and estimating the rate of transmission.

“Most existing studies of reporting bias are limited to students or high-risk populations, or are conducted as ‘laboratory’ settings, so they don’t show how members of the public respond in a ‘real-life’ survey. To our knowledge, our study is the first attempt to look at all the key types of explanation for the gender discrepancy within the same large and representative sample.”