CDC: MRA claims that “40% of rapists are women” are based on bad math and misuse of our data


Feminists often complain, with considerable justification, that Men’s Rights Activists try to turn every conversation about women’s issues into a game of “what about the men?” You’re talking about female rape victims — well, what about the male rape victims?

The trouble with this strategy, from the point of view of the Men’s Rights Activists anyway, is that this little “gotcha” is much less of a “gotcha” then they’d like it to be.

In the case of rape, for example, feminists are well aware that men are raped as well: the “Don’t Be That Guy” ad campaign, which sent so many MRAs into hysterics, focused on male victims as well as female ones. The emergency room rape advocate organization that a friend of mine volunteers for  provides advocacy for victims regardless of gender.

So many MRAs have started playing another game: trying to twist the conversation around in order to cast women as the villains. Rape is a bit tough for them here, since the overwhelming majority of rapists are male. So MRAs talk about the alleged epidemic of female false accusers instead. Or they change the topic entirely and make dead baby jokes (see my post yesterday).

Recently, MRAs have tried a new strategy, seizing on data from The National Intimate Partner and Sexual Violence Survey, a massive study conducted in 2010 under the aegis of the Centers for Disease Control, to claim that “40% of rapists are women.”

This is a claim repeated by numerous MRAs on numerous websites; see, for example, this post by A Voice for Men’s Typhonblue on the blog GendErratic. Here’s the same claim made into an “infographic” for the Men’s Rights subreddit.

Trouble is, this claim is flat-out false, based on an incorrect understanding of the NISVS data. But you don’t have to take my word for it: the NISVS researchers themselves say the MRA “interpretation” of their data is based on bad math. It’s not just a question of different definitions of rape: the MRA claims are untenable even if you include men who were “made to penetrate” women as victims of rape (as the MRAs do)  rather than as victims of “sexual violence other than rape” (as the NISVS does).

I wrote to the NISVS for clarification of this matter recently, and got back a detailed analysis, straight from the horse’s mouth, of where the MRA arguments went wrong. This is long, and a bit technical, but it’s also pretty definitive, so it’s worth quoting in detail. (I’ve bolded some of the text below for emphasis, and broken some of the larger walls of text into shorter paragraphs.)

It appears that the math used to derive an estimated percentage of female rapists … is flawed.  First, we will summarize the assertion and what we perceive to be the basis for the assertion.

According to the web links, the “40% of rapists were women” was derived from these two steps:

1)      Combining the estimated number of female rape victims with the estimated number of being-made-to-penetrate male victims in the 12 months prior to the survey to conclude that about 50% of the rape or being-made-to-penetrate victims were males;

2)      Multiplying the estimated percentage (79%) of male being-made-to-penetrate victims who reported having had female perpetrators in these victims’ lifetime with the 50% obtained in step 1 to claim that 40% of perpetrators of rape or being-made-to-penetrate were women.

None of these calculations should be used nor can these conclusions be correctly drawn from these calculations.

First the researchers clarify the issue of definition:

To explain, in NISVS we define rape as “any completed or attempted unwanted vaginal (for women), oral, or anal penetration through the use of physical force (such as being pinned or held down, or by the use of violence) or threats to physically harm and includes times when the victim was drunk, high, drugged, or passed out and unable to consent.”

We defined sexual violence other than rape to include being made to penetrate someone else, sexual coercion, unwanted sexual contact, and non-contact unwanted sexual experiences. Made to penetrate is defined as including “times when the victim was made to, or there was an attempt to make them, sexually penetrate someone without the victim’s consent because the victim was physically forced (such as being pinned or held down, or by the use of violence) or threatened with physical harm, or when the victim was drunk, high, drugged, or passed out and unable to consent.”

The difference between “rape” and “being made to penetrate” is that in the definition of rape the victim is penetrated; “made to penetrate” by definition refers to cases where the victim penetrated someone else.

While there are multiple definitions of rape and sexual violence used in the field, CDC, with the help of experts in the field, has developed these specific definitions of rape and other forms of sexual violence (such as made to penetrate, sexual coercion, unwanted sexual contact, and non-contact unwanted sexual experiences). We use these definitions to help guide our analytical decisions.

Now the researchers get into the details of the math:

Regarding the specific assertion in question, several aspects of mistreatments of the data and the published estimates occurred in the above derivation:

A.      While the percentage of female rape victims and the percentage of male being-made-to-penetrate victims were inferred from the past 12-month estimates by combining two forms of violence, the percentage of perpetrator by sex was taken from reported estimates for males for lifetime (a misuse of the percentage of male victims who reported only female perpetrators in their lifetime being made to penetrate victimization).  This mismatch of timeframes is incorrect because the past 12-month victimization cannot be stretched to equate with lifetime victimization.  In fact, Table 2.1 and 2.2 of the NISVS 2010 Summary Report clearly report that lifetime rape victimization of females (estimated at 21,840,000) is about 4 times the number of lifetime being made-to-penetrate of males (estimated at 5,451,000).

B.      An arithmetic confusion appears when multiplying the two percentages together to conclude that the product is a percentage of all the “rapists”, an undefined perpetrator population.  Multiplying the percentage of male victims (as derived in step 1) above) to the percentage of male victims who had female perpetrators cannot give a percentage of perpetrators mathematically because to get a percentage of female rape perpetrators, one must have the total rape perpetrators (the denominator), and the number of female perpetrators of this specific violence (the numerator).  Here, neither the numerator nor the denominator was available.

C.      Data collected and analyzed for the NISVS 2010 have a “one-to-multiple” structure (where the “one” refers to one victim and the “multiple” refers to multiple perpetrators).  While not collected, it is conceivable that any perpetrator could have multiple victims.  These multiplicities hinder any attempt to get a percentage of perpetrators such as the one described in steps 1) and 2), and nullify the reverse calculation for obtaining a percent of perpetrators.

For example, consider an example in which a girl has eight red apples while a boy has two green apples.  Here, 50% of the children are boys and another 50% are girls.  It is not valid to multiply 50% (boy) with 100% (boy’s green apples) to conclude that “50% of all the apples combined are green”.  It is clear that only 20% of all the apples are green (two out of 10 apples) when one combines the red and green apples together.  Part of the mistake in the deriving of the “50%” stems from a negligence to take into account the inherent multiplicity: a child can have multiple apples (just as a victim can have multiple perpetrators).

D.      As the study population is U.S. adults in non-institutional settings, the sample was designed to be representative of the study population, not the perpetrator population (therefore no sampling or weighting is done for the undefined universe of perpetrators).  Hence, while the data can be analyzed to make statistical inferences about the victimization of U.S. adults residing in non-institutional settings, the NISVS data are incapable of lending support to any national estimates of the perpetrator population, let alone estimates of perpetrators of a specific form of violence (say, rape or being-made-to-penetrate).

E.      Combining the estimated past 12-month female rape victims with the estimated past 12-month being-made-to-penetrate male victims cannot give an accurate number of all victims who were either raped or being-made-to-penetrate, even if this combination is consistent with CDC’s definition.

Besides a disagreement with the definitions of the various forms of violence given in the NISVS 2010 Summary Report, this approach of combining the 12-month estimated number of female rape victims with the 12-month estimated number of male victims misses victims in the cells where reliable estimates were not reported due to small cell counts failing to meet statistical reliability criteria.  For any combined form of violence, the correct analytical approach for obtaining a national estimate is to start at the raw data level of analysis, if such a creation of a combined construct is established.

So you’re going to need to go back to the drawing board, MRAs.

What is especially distressing here is that the NISVS data could have been the starting point for a serious discussion of male victims of sexual assault by women, which is a real and often overlooked issue. Unfortunately, MRAs have once again poisoned the well by misusing data in an attempt to exaggerate the purported villainy of women and score cheap rhetorical points.

NOTE: A regular in the AgainstMensRights subreddit approached the NISVS researchers with this same question some months back. Unfortunately, the statement they got back from the NISVS contained an incorrect number. The statement I’m quoting here corrects this number and adds more context.

I can provide contact info for the NISVS representative who got back to me on this to any serious (non-troll) person who requests it.

About David Futrelle

I run the blog We Hunted the Mammoth, which tracks (and mocks) online misogyny. My writing has appeared in a wide variety of places, including Salon,, the Washington Post, the New York Times Book Review and Money magazine. I like cats.

Posted on October 29, 2013, in all about the menz, antifeminism, evil women, misogyny, MRA, playing the victim, rape, rape culture, reddit, sexual assault, TyphonBlue and tagged , , , , , , , , . Bookmark the permalink. 1,000 Comments.

  1. Oh my gosh, he’s, like, 14!

  2. It’s 5 am in the UK. Graeme, go to bed before your mum notices the light on in your room and takes away your biscuit privileges for the month!

  3. This is the thread that never ends,
    It just goes on and on, my friends!
    Cause some trolls just keep necroing it,
    Not reading what it says,
    And they’ll just keep on necroing it (like jerks!) forever just because…

  4. RE: Graeme

    Yeah, random strange dude, you totally know more about statistics than the fucking CDC. You know so much, you don’t even have to give any evidence, just categorically state your opinion as fact.

    Do you love necroing threads that badly?

  5. How old are you, anyway?

  6. Dear Grame, I’m sorry to inform you that cross-posting to a different thread after a flounce incurs a -4 point penalty.

    Your score has fallen from the “vile place” inspired height of +4 to an inconsequential 0.

    Each further post on either of these threads will result in the standard -2 deduction advised by Katz long ago.

    Have a great day!

  7. Cross-threading is bad and sad.

  8. Contrapangloss is all over this. That flounce lasted precisely 15 minutes.

  9. kittehserf - MOD

    Hey troll, I’m dumping your comments. Piss off.

  10. Yay for kittehserf!

  11. In this post, “rape” includes penetrating someone without their consent AND making someone penetrate your or someone else without their consent.

    The CDC’s explanation for why the data does not show that 40% of rapists are female is completely legit. But it’s important to realize that the argument works both ways. The data also does not show that the majority of rapists are male. The data DOES show that the majority of rapes are committed by men, but there’s no way to tell whether this means more male rapists or fewer male rapists with more victims per rapist. As the CDC itself admits, the data doesn’t tell us what the population of rapists looks like.

    On the other hand, their explanation about the omitted cells is just plain silly. While it does mean that there will be some error in the estimation from omitting these cells, the CDC’s own analysis encounters this same error. Moreover, those cells don’t have numbers specifically because the number of people reporting such incidents were so small that the statistics could not be trusted. This means that the two cells with numbers do account for the vast majority of responses, and thus the 50/50 estimate of the VICTIM population within the past 12 months is very close to accurate. It is also still clear that most male rape victims are raped by women.

    So while some specific claims of the MRAs are ill-founded, the raw data still indicates that treating rape as something that is almost universally done by men to women is very flawed, as is assuming that men who are raped are usually only raped by other men. The raw data shows quite clearly that female-on-male rape is a lot more common than most people realize.

    So go ahead and bash MRAs. I agree that they made their point VERY poorly. But there is still a point. Female-on-male rape is common enough that it really should be recognized in our campaigns. Instead of calling for efforts to teach *men* not to rape, we can insist on teaching *people* not to rape. We can make posters that do accurately reflect the demographics of rape-victims, and have posters that do tell women that it’s rape if they have sex with a drunk guy. We can encourage teaching EVERYONE about what does and does not constitute consent, and teaching EVERYONE not to take advantage of drunk people, instead of singling out men as the sole focus of the campaign.

    Let’s not use the MRAs’ terrible lack of point-making skills as an excuse to not address the very real issue of not representing female-on-male or female-on-female rape in educate-the-perpetrator type programs.

  12. “The data DOES show that the majority of rapes are committed by men, but there’s no way to tell whether this means more male rapists or fewer male rapists with more victims per rapist.”

    Okay, lets assume these are our two possibilities, shall we?

    Possibility one: Male and female rapists rape about the same amount of people. In this case, men are the majority of rapists: In that case, teaching men not to rape is still as valid as it ever was.

    Possibility two: Male rapists rape far more people in a lifetime than female rapists do. In this case, a single male rapist causes more problems than a single female one. Therefore, stopping a single male rapist helps the community as a whole more than stopping a single female rapist. In this case too, the validity of current programs has not changed.

    Now, you imply that this post wants us to “not address the very real issue of not representing female-on-male or female-on-female rape in educate-the-perpetrator type programs.” This is misses the point made at the end of the post which reads: “What is especially distressing here is that the NISVS data could have been the starting point for a serious discussion of male victims of sexual assault by women, which is a real and often overlooked issue. ” As you can see, he acknowledges that there is a conversation to be had.

    “treating rape as something that is almost universally done by men to women”

    You are arguing against a point which was not made in the article you’re commenting on. This makes it very difficult for your post to be viewed as anything other than a distraction and a strawman.

  13. Looks like they did their math correctly. If they didn’t, then why can’t the CDC say the actual percentage?

    LMAO, you can deny facts all you want, but those numbers, taken EXACTLY as provided by the CDC, leads to 40%.

  14. Only MRA’s with an agenda say women rape 40%. Check out this video on youtube. It explains how to read the study properly.

  15. You ROCK!
    I just debated an MRA who used this 40% stat and this was the perfect resource. Thank You! Bravo!

  16. You forgot something:Men are much more likely to forget and reframe violence committed against them by women that the reverse. Therefor, you need to control for that by adjusting the ratios.

    That, in fact was explained very well and thoroughly in a video made by that same typhon-blue..

    Then again, you already know that.

  17. The CDC is quite correct that the lifetime number of “made to penetrate” (MTP) exclusively by females cannot be assumed to apply to the given year.

    The mistake is to assume that the 12 month number is likely to lower. In a typical year however it is likely to be higher. Here is the reasoning:

    Any man who was MTP this year who was MTP exclusively by females over his lifetime will have been MTP this year by a female.

    Some of the men MTP this year who were not exclusively MTP by females in their lifetime will have been MTP by females this year.

    So if the CDC’s numbers are to be believed, that would imply the likelihood that more than 40% of the rapes/MTP’s in a year were of male victims.

    For what it is worth, I think this study has a lot of problems, especially vaguely or ambiguously worded questions. Things like lumping together being “kissed you in a sexual way when you didn’t want it to happen” with being “fondled, groped, grabbed, or touched you in a way that made you feel unsafe”. Or the question about drug facilitated sex that is worded in such a say that it could easily be interpreted to include any sex under the influence of alcohol. These sorts of issues could easily inflate a lot of the numbers including MTP.

    Whatever the numbers, victims are victims and should be treated with compassion.

  18. I’m so fucking tired of this thread being necro’d.

    Not sure what your trying to get at, statschecker, but according to the CDC study:

    Approximately 1 in 21 men (4.8%) reported having been made to
    penetrate someone else in his lifetime (Table 2.2). Too few women reported being made to penetrate someone else to produce a reliable estimate (Table 2.1).

    They found 1/71 men had been the victims of penetrative rape in their lifetimes. I don’t know here you are getting that 40% number.

    Frankly, 1/7 billion (or whatever the population of the planet currently is) being the victim of rape or sexual assault, man or woman, is too high.

  19. Here’s the relevant section on penetrative rape. My phone is being wonky:

    Approximately 1 in 71 men in the United States (1.4%) reported having been raped in his lifetime, which translates to almost 1.6 million men in the United States (Table 2.2). Too few men reported rape in the 12 months prior to taking the survey to produce a reliable 12 month preva- lence estimate.

  20. Ah, the most beloved post in WHTM history returns yet again.

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