Women are statistically sluttier than men. Psych. Actually, if we measure sluttiness by the number of partners you’ve slept with, men and women are equally slutty by definition.
Why so? Consider a population with an equal number of men and women. The total number of heterosexual hookups is H. The average number of hookups for men is H divided by the number of men, and likewise for women. Since these numbers are the same, the average man always has exactly the same number of partners as the average woman. It’s impossible for these numbers to be different as long as there are roughly equal numbers of men and women.
So Business Insider is right to point out that something smells fishy when the averages don’t match. Psychologists point to cognitive shortcuts that bias our estimates – women tend to recall every encounter while men approximate – but most would call it lying. If you lie to your partner you have bigger problems than your sexual history (though maybe they shouldn’t have asked). But what if you lie to a data collector?
Then we’ll see statistical averages that are simply not possible. Various newspapers will embarrass themselves with their lack of math skills by reporting impossible statistics uncritically, and official datasets will be useless. Any researcher interested in sexual activity will be forced to do field experiments.
With a few assumptions, the savvy researcher can get some traction out of existing datasets before hitting the field. First assume that men over-report their number of partners and women under-report. This gives us upper and lower bounds, between which the true number must lie.
According to the Add Health dataset, the average late-20s American has between 1.4 and 1.9 heterosexual partners per year (the lower bound being women’s reported average and the upper bound being men’s). Excluding couples, the range jumps to 1.6 to 2.3. These discrepancies are smaller than implied by the ‘rule of three’ from American Pie, and smaller than the two- to four-fold ratio found in psychology studies. Since the numbers roughly add up, let’s take an uncritical first look at the distributions.
More women report having one or no partners per year, and more men report having any number more than one. Around 12% of either gender report 10 or more partners (which may qualify you for slut status). At the extreme end of the distributions (not shown here), one woman reports sleeping with 75 men while her male counterpart only recalls 50 women.
Next we corroborate the numbers with another dataset: the National Survey of Family Growth. The NSFG topcodes reported sex partners for men (whose privacy must be maintained) but not for women (who must be shamed into chastity). So while we observe the full distribution of reported partners for women, for a man who reports seven or more partners we can’t tell if he has had exactly seven, or seven hundred. But let’s use this limitation to our advantage.
Since the total number of heterosexual hookups must be the same for men and women, let’s make an assumption about the men who report more than seven partners: on average, they’ve been with 8.8 women in the last year. This makes the number of hookups equal across genders (assuming that all women are perfectly honest).
Then the average number of partners in the last year equal to 1.2 for both genders (a bit lower than in the Add Health dataset). Now let’s look at couples and singles separately.
By construction the total number of hookups is equal. But looking at activity across marital status, we become suspicious. Spouses of both genders report more than one partner on average. Married men report more partners than their wives do, and it seems single women are picking up the slack. If we generously assume that married men have sex with their wives and at most one other woman, then 9% of husbands have had an extramarital partner in the last year (compared to 4% of wives). And this is only what they admit to!
So who are the sluts? Maybe the men who cheat on their wives. Maybe the single women who they’re apparently cheating with. Maybe “slut” is an outdated and negative term used to cast shame on people we’re jealous of. The numbers can’t tell us who’s sluttier, but can only colour our opinions. My opinion is that you’re all sluts.
Writer: Herr K
Thanks to Alison Mah for executive redaction. Remaining errors are my own.
 The ‘rule of three’ states that men over-report their number of sexual encounters and women under-report – both by a factor of three: https://www.youtube.com/watch?v=9oVoJMVsKtk. This would imply an upper bound nine times greater than the lower.