Why Men Report More Sex Partners than Women
Get the world’s most fascinating discoveries delivered straight to your inbox.
You are now subscribed
Your newsletter sign-up was successful
Want to add more newsletters?
Delivered Daily
Daily Newsletter
Sign up for the latest discoveries, groundbreaking research and fascinating breakthroughs that impact you and the wider world direct to your inbox.
Once a week
Life's Little Mysteries
Feed your curiosity with an exclusive mystery every week, solved with science and delivered direct to your inbox before it's seen anywhere else.
Once a week
How It Works
Sign up to our free science & technology newsletter for your weekly fix of fascinating articles, quick quizzes, amazing images, and more
Delivered daily
Space.com Newsletter
Breaking space news, the latest updates on rocket launches, skywatching events and more!
Once a month
Watch This Space
Sign up to our monthly entertainment newsletter to keep up with all our coverage of the latest sci-fi and space movies, tv shows, games and books.
Once a week
Night Sky This Week
Discover this week's must-see night sky events, moon phases, and stunning astrophotos. Sign up for our skywatching newsletter and explore the universe with us!
Join the club
Get full access to premium articles, exclusive features and a growing list of member rewards.
Most surveys about sex find impossibly that men have had far more partners than women, typically two to four times as many.
Either there are a bunch of phantom females out there, or somebody is lying.
Or perhaps people just have lousy memories about these things.
Psychologist Norman R. Brown at the University of Michigan has done several studies on the apparent flaw in these surveys. The latest was a web-based survey of 2,065 heterosexual non-virgins with a median age in their late 40s.
The women reported on average 8.6 lifetime sexual partners. The men claimed 31.9.
Rather than let it go at that, Brown and his colleagues later in the survey asked the participants to rate the truthfulness of their response. About 5 percent—both men and women—said they lied. In addition, more than 10 percent said they knew their answer wasn't accurate.
"They gave an answer and then two minutes later admitted they had lied about the answer," Brown said.
Get the world’s most fascinating discoveries delivered straight to your inbox.
But there's more to the discrepancy. Men and women use different methods to calculate their past dalliances.
Women rely on a raw count, a method Brown says is known to result in underestimation.
"They tend to say, 'I just know,' and if you ask them to explain how they know, they say, 'Well, there was John, Tom, etc.'"
Men also rely on a flawed strategy.
"Men are twice as likely to use rough approximation to answer the question," Brown said. "And rough approximation is a strategy known to produce over-estimation."
Then again, maybe Brown's study is flawed, too.
His next survey will be done by telephone, to find out if people lie and fudge as much in that medium, or if the Web-based surveys invite such behavior. The self-proclaimed liars "could be liars who lie about lying," he said.
Robert is an independent health and science journalist and writer based in Phoenix, Arizona. He is a former editor-in-chief of Live Science with over 20 years of experience as a reporter and editor. He has worked on websites such as Space.com and Tom's Guide, and is a contributor on Medium, covering how we age and how to optimize the mind and body through time. He has a journalism degree from Humboldt State University in California.

