Debunking Denialism

Defending science against the forces of irrationality.

A Voice for Men on Rape Statistics: Confusing Life-Time Prevalence with Incidence


In the online conflict between certain specific men’s rights activists (MRAs) and certain specific radical fringe feminists, no part have their intellectual integrity fully intact. Elements on both sides misunderstands statistics and basic biology and they also appeal to pseudoscience to justify their political ideology. For example, some fringe radical feminists, particularly those with postmodern inclination, may devalue biological partial explanations or subscribe to the notion of a blank slate. Similarily, some men’s rights activists propose superficially plausible evolutionary accounts of the origin of gender roles from the 1940s, but in the end, cannot provide any scientific evidence for their highly speculative accounts (making them a just-so-story).

I think that gender equality is a moral necessity, but it is terribly tedious and tiresome to read the spiraling conflict between extremists, especially when they make embarrassing rookie mistakes.

One such mistake is made by the blogger Phil in Utah over at the A Voice for Men blog in a blog post about rape statistics that confuses life-time prevalence with incidence. Phil in Utah writes:

Statistic: “1 out of every 4 women will be raped in her lifetime.”

Truth: Ah, here’s the doozy. I’m sure we’re all familiar with the source of this statistic: a study by Mary Koss that has been discredited countless times. Around three-quarters of the women she identified as having been raped did not consider themselves victims of rape, and almost half of them had sex with their supposed attackers after the event identified as a rape had occurred.

I do not really know enough about the Mary Koss study to make an informed argument, but surely, rape has to be defined as objective as possible and not solely be based on personal opinion? So the argument that some of the women did not consider it rape, therefore it should not be counted as rape, seems wrong. Obviously you can be subjected to a crime even though you are not aware that it is considered a crime. A rose by any other name…

Let us look at some rape statistics from the CDC. In their National Intimate Partner and Sexual Violence Survey (NIPSV), they reached the following conclusion with regards to rape prevalence among women. From the executive summary:

Nearly 1 in 5 women (18.3%) and 1 in 71 men (1.4%) in the United States have been raped at some time in their lives, including completed forced penetration, attempted forced penetration, or alcohol/drug facilitated completed penetration.

Now, rape prevalence will differ depending on how inclusive the definition of rape is (varies between countries), but according to the definitions used by the CDC, it is around 18% of women in the U. S. Although not exactly 1 in 4 (25%), it is fairly close. With that in mind, let’s see how Phil in Utah tackles U. S. rape prevalence:

So, what do statistics collected from non-feminist sources say? Well, let’s try the FBI statistics. According to an FBI report, which did not account for differing definitions of rape, whether or not the rapes were convicted, or whether or not female-on-male rape was included, the United States had a rate of 29 reported rapes per 100,000 people in 2009. That’s not going to get us to 25%, but I’m feeling generous, so let’s look at the country with the highest rate of rape in the past decade–South Africa, with a rate of 116 rapes per 100,000 people in one year. Percentage wise, this is .1% of the population. Now, I’ll admit that I’m worse at math than anything else in the world, but even I know this isn’t even close to “1 in 4″.

Here is the problem with that argument: the CDC looked at rape prevalence (actually, life-time prevalence, see below), whereas the data cited from the FBI report (and the South Africa argument) looked at rape incidence. This seems like a minor quibble, but it is of utmost importance. Here is why.

Prevalence and incidence are two key concepts within epidemiology and medical statistics. Let us look at how these two concepts work when it comes to, say, HIV. The prevalence of HIV tells you the total number of HIV cases (usually in % of total population). The incidence of HIV tells you the number of new cases of HIV arising during a certain time period. As we can see, it is really important to not confuse these different metrics. For HIV prevention, we want to focus on getting the incidence down. Getting the incidence down is one way to prevent the prevalence from rising, but obviously we do not want HIV patients to die, so we cannot just focus on trying to get the prevalence of HIV down with any means necessary.

As an added complication, life-time prevalence of rape looks at what proportion of the population that has been raped sometime in their life. This means that we must separate discussions of the number of new cases of rape per time unit (rape incidence) with discussions about the proportion of the population that has been raped some time in their life (life-time prevalence of rape). Technically it is the proportion that has been raped some time during their life up to the time period the study is being carried out. Obviously, scientists cannot draw on non-existent, future statistics.

So to sum up, the reason that the argument laid out by Phil in Utah fails is that it confuses prevalence with incidence. Phil in Utah seems to understand this when making the following rebuttal to a perceived counterargument:

“But wait!” the feminists are saying, “Most rapes are never reported to the police!” Well, I’ve heard a number of different figures on just how many. Some say 45%, some say 60%, and some even say 80%. But hey, I’m feeling EXTREMELY generous, so despite the fact that feminists are basing these numbers off evidence that is dubious at best, I’ll go with the highest estimate. .1 times 5 is…half of one percent. In other words, one-fiftieth of what feminists claim it is.

Now, I hear them whining that I missed the key phrase “In their lifetime”. Okay, since empirical data shows that rates of rape drastically decrease after the victim turns 45, whether they are male or female, in prison or out, I’ll just be accounting for a 30-year window. Sorry, feminists, but even my generosity has its limits. I’m not going to pretend that the wackos who rape grannies aren’t extreme outliers. This means that 15% of South African women will be raped in their lifetimes. A grisly figure to be sure, but then again, this is South Africa we’re talking about–it has the second-highest crime rate in the world. The rate of rape in the U.S. is one-quarter of that, so in our most generous of moods, it is correct to say that 3.75% of women will be raped in their lifetimes. I’m puzzled as to how that can be mistaken for 1 in 4.

Sadly, Phil in Utah falls prey to the same problem. He is making the argument that since the rape incidence in U. S. is 1/4 of the rape incidence in South Africa, the rape prevalence in the U. S. has to be 1/4 of the rape prevalence in South Africa. This is of course wrong, as there is nothing that says that changes rape incidence in the U. S. follows change in rape incidence in South Africa. The latter has been strongly politically instable for decades, so that is a clear confounder.

The life-time rape prevalence in South Africa seems to be calculated by Phil in Utah as summing up the rape incidence in South Africa (together with a modifier for rapes that go unreported) over 30 years (0.5*30 = 15). However, this is not the same as life-time rape prevalence, which was, as we saw, what proportion of the population that has been raped sometime in their life.


Life-time rape prevalence for women in the U. S. is around 18% according to the CDC.

Phil in Utah makes the following statistical errors in his reasoning: (1) confuse (life-time) prevalence with incidence, (2) confuse (life-time) prevalence with the sum of incidence over 30 years and (3) thinks that 1/4 of the incidence implies 1/4 of the prevalence (really a version of the first statistical error).

To make convincing statistical arguments, one should preferably understand the relevant statistics. Otherwise, one risks making embarrassing statistical errors.

19 responses to “A Voice for Men on Rape Statistics: Confusing Life-Time Prevalence with Incidence

  1. Mipochka August 25, 2012 at 14:31

    Oh how interesting. Causes me to remember the time I was raped in the Air Force, and then the time my birth mother told me she couldn’t tell me who my father is “because it was a rape.” That’s if I don’t think of the stuff my adoptive dad used to like doing out in the woods, first. There’s also the rapes that occurred to other girls on campus – oh wait, how many was it – while I was in college … Doesn’t feel like “incidence” or “prevalence” – how strange…I’m guessing from your thoughtful and sensitive article that you understand each time when people talk about rape that there might be victims right next to you…

  2. Mipochka August 25, 2012 at 14:33

    Oh, and none of the first three events I mention were ever reported to police…but I can’t speak for others because I’m not one those radicals so I’m just going to end by reporting that I”m unsubscribing, bye, ’twas nice while it lasted….

  3. Emil Karlsson August 25, 2012 at 15:06

    I disproved a common anti-feminist “argument” that is used to minimize the problem of rape…and you think I was being insensitive to rape victims?

  4. Egalitarian August 25, 2012 at 17:26

    The “1 in 71 men have been raped” stat from the CDC survey doesn’t tell the whole story. It defines “rape” as the attacker penetrating the victim, which excludes women who use their vagina to rape a man (rape by envelopment) which is counted as “made to penetrate”. The very same survey says “1 in 21 men (4.8%) reported that they were made to penetrate someone else,” which is far more than 1 in 71. Also, the study says that 79.2% of male victims of “made to penetrate” reported only female perpetrators, meaning they were raped by a woman.

    The above, lifetime stats do show a lower percentage of male victims (up to 1.4% rape by penetration + 4.8% made to penetrate = 6.2%) than female victims (18.3%) although it is far more than the 1 in 71 you stated. However, if you look at the report’s stats for the past 12 months, just as many number of men have been “forced to penetrate” as women were raped, meaning that if you properly define “made to penetrate” as rape, men were raped as often as women.

    • Emil Karlsson August 25, 2012 at 17:49

      You did not actually address the argument I made in this blog post. Do you understand the difference between prevalence and incidence? Do you accept that the blogger Phil in Utah confused these two metrics in his arguments?

      The 1 in 71 figure is not something I stated, but something I quoted from CDC. I also, after the quote, pointed out that this figure depends on the definition of rape. Did you manage to read that far?

      The report does state that the life-time prevalence in being made to penetrate someone else is 4.8% and if we add that to 1/71, we do get 6.2%. This, however, is still a far cry from around 18%. In reality, the life-time prevalence of rape for men is irrelevant for the accurate characterization of the life-time rape prevalence of women. The fact that around 6% of men are raped does not mean that the 18% figure drops to 4% as Phil in Utah wants to have it.

      For that particular year, it does seem as if the number of men who reported being forced to penetrate is about equal to the number of females who have been raped. However, that is a single data point and tells us nothing about how it looks overall. There may be certain days out of the year that the temperature in Sweden and Australia is the same. Does that mean that the two countries have identical climates? No. That means that it is better to look at longer time periods; that is why people care about life-time prevalence in the first place.

      For life-time prevalence, it is about 5.5 million men who have been made to penetrate and about 22 million women who have been raped (pp. 18-19). So even when we define both as rape, women carry the stronger burden.

      This is of course completely irrelevant to the point of my post, which was that the blogger Phil in Utah confuse prevalence with incidence.

    • Egalitarian August 25, 2012 at 18:06

      My point is that your “1 in 71″ quote is misleading. Your offhand comment of “Now, rape prevalence will differ depending on how inclusive the definition of rape is…” does not make it even clear or even suggest that if rape is properly defined, the prevalence is far higher than 1 in 71 (actually 1 in 16). Instead, readers are being led to think “oh, only 1 in 71 men have been raped,” which is inaccurate.

      Yes, I accept that Phil in Utah confused incidence and prevalence, just like most discussions of the CDC study, outside of MRA sites, have confused rape with being penetrated and ignored the “made to penetrate” numbers.

    • Thaumas Themelios August 25, 2012 at 18:26

      Egalitarian, this may be an example of ‘violent agreement’, where both you and Karlsson agree on the facts, but differ only in some secondary feature (in this case, emphasis on which part of the topic). So it may look like you disagree with Karlsson, but I don’t think you do, actually.

      It’s just that the prevalence or non-prevalence in males is *irrelevant* to the main point of Karlsson’s article. For you, it may be an important issue that you want to pursue, but for the purpose of this article, Karlsson’s quoting of the 1 in 71 is merely incidental (he could have left it out entirely and still made his entire point), and not part of his argument.

      I do happen to agree with you on one point, that by quoting it out of context, and not explaining the context thoroughly, some people *may* go on to use that as a basis to claim, “Oh, it’s only 1 in 71.” *But*, if they did do this, then they would be guilty of perhaps even worse fallacies: Cherry picking, quote mining, etc. Needless to say, Karlsson would debunk their misleading quote just as thoroughly as he’s debunking this current fallacy of misusing statistics. It would not be the fault of Emil Karlsson, but the fault of the quote-miner.

      However, as I myself try to practice not repeating false/misleading information, I could see that you would have a stylistic argument that it is ‘better’ either not to quote the 1 in 71 at all, or to only quote it in complete context. I just don’t see that as an ethical issue. I think Karlsson’s article is clear enough on its own (I was not mislead, myself), so I would understand if he felt no need to modify or amend it on this issue. (And I have been picky about misleading wording in articles before (recently, in fact), so I’m not merely dismissing your point. I just don’t think it ‘crosses the line’ in this instance.)

    • Emil Karlsson August 25, 2012 at 19:23


      it should be obvious that these figures refer to rape as defined in the CDC report itself. Had I made a post that focused on the difference in rape statistics between men and women, I should have posted and discussed the definitions used. But this was not the point of the post.

      The concept of “rape as properly defined” is not uncontroversial (at what level of intoxication are people unable to give informed consent? Does subtle psychological manipulation count? etc.) and it is certainly not as easy as you make it out to be.

      Even using the most inclusive definition of rape possible from the CDC data (i.e. rape + other sexual violence):


      Rape: 21,840,000
      Other Sexual Violence: 53,174,000

      = ~75 million victims


      Rape: 1,581,000
      Other Sexual Violence (this includes being made to penetrate): 25,130,000

      = ~27 million victims

      This data is from life-time prevalence. For the past 12 months in 2010 cannot be reliably compared because the estimate for men where not included because of relative standard error > 30% or cell size < 20%.

      So in order to get the numbers to come out the way you want them to, you would be required to, with the figures already known, define rape in such a way that the figures come out the way you need them to. In other words, you would decide your own result.

    • Egalitarian August 25, 2012 at 20:22


      You are right, I don’t disagree with Karlsson on the facts, but I would argue that quoting the “1 in 71″ number for men is just as misleading as mistaking incidence with prevalence. Misleading statistics have the same impact whether they are due to factual errors, incorrect interpretations, or questionable definitions. I agree that it would have been reasonable to leave out the “1 in 71″ number entirely.

    • Emil Karlsson August 25, 2012 at 20:57

      If I had written

      Nearly 1 in 5 women (18.3%) [...] in the United States have been raped at some time in their lives, including completed forced penetration, attempted forced penetration, or alcohol/drug facilitated completed penetration.

      …then I am sure someone would have accused me of trying to cover up the rape of men or minimizing the rape of men by quoting selectively.

      I guess there are some cases where you just can’t win.

    • Thaumas Themelios August 26, 2012 at 04:57

      I think you’re right, there, Emil. You can’t please everyone. The main thing is that you quoted it correctly (though perhaps not perfectly; and perfection is a rotten standard to live by anyway), and provided a link for people to check on their own. That’s completely fair, in my personal opinion. You didn’t actively misrepresent anything, and you’re aware of the subtleties of the reports and the statistics, and even gave notice that the numbers depend on the definitions used.

      @Egalitarian, I’m not unsympathetic to your desire not to mislead in this way, but I respectfully disagree that Karlsson’s quoting is “just as misleading as mistaking incidence with prevalence”, due to the fact that the quoting was a) incidental, not actually relevant to his point, and b) surrounded by enough warnings (e.g. that rates depend on definitions) and references (link to the original research) that an intellectually honest and responsible person would not reasonably use such an incidental quotation without first double-checking the source.

      That intellectually *dishonest* or careless people might misuse it that way is not the fault of Karlsson, but of such people themselves. And, as yet, such misuse of Karlsson’s quote is currently only hypothetical, and not actual; so again, I can’t say as he’s done anything wrong or unethical here. This is simply not on the same level as the misuse/misunderstanding of statistics regarding incidence and prevalence.

      The only occurrence of the 1 in 17 figure is *within* the quote itself, and Karlsson does not refer to it at all in his own words. He is not using it inappropriately, because he is not *using* it at all, except as incidental context of a quote about *another* statistic.

      “Misleading statistics have the same impact whether they are due to factual errors, incorrect interpretations, or questionable definitions.”

      I agree, but we should (IMO) focus our efforts on correcting actual misuses of such statistics, and on the people who actively use them inappropriately. I disagree that Karlsson’s quote here qualifies as an actual misuse of statistics, due to the reasons I gave above.

      And also, to repeat: If people wander on by and read random numbers from webpages and use that kind of unskeptical and uninformed method to base their worldviews upon, then *that* is the real problem — people thinking and acting irrationally and unreasonably. *That* is the problem I am focused on correcting. If people were better skeptics and critical thinkers (which is not actually that hard to do), then this entire side-issue you brought up would be an entirely moot point. Emil Karlsson’s article here is one example of an effort to help address that problem. As such, IMO it’s part of the solution, not part of the problem. We would all do well to think as clearly as possible on such contentious issues such as this one. That’s the point.

  5. Thaumas Themelios August 25, 2012 at 18:10

    Very sorry to hear about your experiences, Mipochka. I hope more people feel brave enough to bring about such experiences to light. It is very important.

    Unfortunately, I think you may be burning a good bridge here, perhaps without realizing it. Just as it’s important to hear about the experiences of people who have been raped, it is also important to understand and use the science and statistics that have studied rape incidence and prevalence correctly.

    That is the job that Karlsson’s article above does so well, and I do not think I’m alone when I say that I found his analysis very helpful, which makes me more confident to speak out against the misuse of such statistics in the future.

    The reason this kind of analysis is important *in addition to* personal experience reports such as yours, is that one of the best ways to defuse an ongoing argument with people who are entrenched in their positions (such as some MRAs, and also some ‘radical’ feminists — but really any person entrenched in any position) is to appeal directly to the best evidence we have available about the objective reality of the macro-scale situation, such as by examining statistics about rape from national, international, or scientific studies.

    When people are entrenched, they go back and forth, “I’m right!” “No, I’m right!” with no way of resolving the conflict, *because* they do not rely on reliable evidence to come to their positions. It is only when people are forced to account for their positions by appealing directly to evidence that we can have a strong hope of resolving the conflict.

    The more people rely on their own personal convictions, the worse the disagreement gets. The more people rely on reliable, objective evidence of the actual *reality* of the situation, the more people will come to agreement *about* that reality.

    Karlsson’s article here (and his whole blog, really) is using this strategy to find out what the reliable primary sources of information (government studies, international studies, scientific studies, etc.) and to debunk the claims made by people who wrongly ignore and deny what’s *real* in favour of what they want to believe.

    In the end, reality always wins, so the side(s) that embrace reality are going to be proven right again and again. Karlsson is on the side of reality (and me too, or so I strive to be, anyway), so it’s unfortunate that you seem to be burning this bridge with him when he’s really on your side. I hope you reconsider, sometime.

  6. Pingback: An Intellectual Re-evaluation of the “Schrödinger’s Rapist” Analogy « Debunking Denialism

  7. itry2brational January 30, 2013 at 17:35

    I’ve read the article most of the discussion but come away not knowing what to believe! Can we get a summary of the best information available which is as fair as possible? Incidence of rape per year for male and female which uses the fairest definition(s) as possible is a solid start.

  8. Luís Henrique March 19, 2013 at 15:58

    One important question would be, is the definition of rape by the CDC the same as those in the penal codes? Considering the US has many different penal codes, that would strike me as almost impossible.

    You say, “Obviously you can be subjected to a crime even though you are not aware that it is considered a crime”. True, but if a large part of the population disagrees with the law – which theorically, in a democracy, should be the expression of the will of the population – then who’s “wrong”, the law or the population?

    • Emil Karlsson March 19, 2013 at 18:24

      I am not an expert on the American legal system, but I think rape is a state crime and so definitions could potentially vary across states.

      Even if a large part of the population disagrees with a law, the law is still active until it has been overturned. The USA is a constitutional republic, not a direct democracy.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s


Get every new post delivered to your Inbox.

Join 144 other followers

%d bloggers like this: