Some Statistics on Rape of Adult Women in the U.S.

A previous post discusses the meaning of rape, with a particular focus on adult female victims. This post continues that discussion, turning from the definition of the crime to the tallying of its occurrences.

The focus on adult females does not imply a lack of concern about rapes of children and of men and women in prison and the military. Rather, this post is preparation for a later post on the use of statistics for gender-related purposes.

Note that this post criticizes certain misuses of relevant data by the Obama Administration. It would be a mistake to infer, from such criticism, that I must be a Republican. This post simply attempts to identify certain realities related to research on rape.


This post provides a look at statistics pertaining to the rape of adult women in the United States. Sections of this post examine the difficulty of obtaining good data, the lifetime prevalence of rape, the year-by-year incidence of rape, the age distribution of female rapes, the college age group in particular, and some remarks on perpetrators. Much more could be said on these matters and on others not broached (e.g., types and rates of injury resulting from rape; personality characteristics of rapists).

As the following discussion indicates, many questions in this area remain unsettled. There are numbers falling within a more or less narrow scope — on, for instance, the lifetime prevalence of rape — yet most of those numbers suffer from various weaknesses, including the difficulty of their underlying assumptions and the paucity of solid and/or consistent findings to support them. Far from providing a foundation, such numbers are invariably tentative, offered for discussion purposes, and subject to potentially significant revision.

Some of the key numbers estimated in the following discussion are as follows:

  • At present rates, roughly one out of every six or seven women (i.e., approximately 14-16%) will be raped at some point in their lives.
  • An estimated five women per thousand are raped each year.
  • Of the women who will ever be raped, about 43% (i.e., about 6% of all women) will be raped for the first time before they turn 18. These women are 2.5 times more likely to be raped again, as adults, than those who were first raped at age 18 or later.
  • Of the women who are not raped by age 18, about 92% will never be raped. Of those who reach age 35 without being raped, about 99% never will be.
  • Perhaps as many as 4% of women are raped in college.
  • For every woman raped by a stranger, seven to ten women are raped by someone they know.

The concluding discussion also suggests that a small subgroup of perhaps 5% of men can be responsible for a disproportionately large share (e.g., 35%) of violent acts.

These numbers are, again, estimates. Comments and suggestions for improvement are welcome.

Difficulty of Obtaining Good Data

Virtually anyone who has earned a graduate degree in social science, and a good many other undergraduate and graduate students as well, have probably been exposed to the reality that it can be difficult to obtain good data on social phenomena.

If you get your data from official reports, you run into one kind of problem: the official data may understate or overstate the realities. For example, governmental statistics indicating the numbers of men arrested for rape could overestimate the number of rapists, if you don’t adjust for those who were arrested more than once; arrests would include cases of false accusation that would drop out if you were to focus instead on convictions; then again, there are lots of reasons (e.g., plea bargains) why rapists who could be convicted aren’t. There are also problems with collecting data from potentially incompatible data sources (e.g., asking different questions, recording different kinds of information) as well as records that have simply been falsified (e.g., to create an illusion of progress in fighting crime, e.g., Yung, 2014).

So getting rape data from official reports is problematic. Likewise for data provided by agencies that provide services to victims. (See Domestic Violence, Sexual Assault, and Stalking Data Resource Center.)

But where else can you go for information? You can ask women if they were raped. But here, again, there are complications. Fisher (2009) observes that two different research approaches yield very different estimates of the frequency of rape. The Bureau of Justice Statistics (BJS, 2011) concurs:

Challenges exist in the collecting of self-report data [i.e., the data obtained from interviews and questionnaires that ask women about their experiences] on rape and sexual assault. For almost two decades, there have been a number of competing national estimates of the level and the change in level of rape and sexual assault. The official estimates of these crimes released by BJS and based on the National Crime Victimization Survey (NCVS) have typically been lower than estimates obtained from surveys contracted for by other federal agencies and by private groups. . . .

Some of the differences in these estimates result from more and less inclusive definitions of rape and sexual assault. The NCVS, for example, emphasizes felony forcible rape, while the National Women’s Study (NWS) employs a much more inclusive definition. Even when the surveys use comparable definitions, however, the methodology used to elicit reports of these events can differ dramatically and produce very different estimates of the incidence of these crimes.

Such differences in methodology can be driven by researchers’ preconceptions. Consider, for example, the reasons that female rape victims offered, when asked why they did not report their rapes to the police. In the National Violence Against Women Survey (NVAWS) conducted by the Centers for Disease Control and Prevention (CDC, 2006, p. 35), leading reasons for not reporting the crime included “fear of rapist,” “police could not do anything,” and “police would not believe me or would blame me.” Those sorts of reasons suggest that problems in public perceptions and/or in law enforcement are preventing the reporting of crimes that should be reported.

But victims also offer other reasons for not reporting rapes — reasons that have more to do with the victim’s preferences in how to handle the matter. For example, in that same study, another leading reason was, “Minor incident; not a crime or police matter.” Some observers, encountering that rationale, will be inclined to accept the woman’s judgment that, in her view, it was in fact a minor incident. Others, by contrast, will assume that the woman is mistaken — that, in effect, she is not qualified to make her own decisions as to the importance of the episode.

Similarly, in a discussion of another study, the National Institute of Justice (NIJ, 2008) said this:

Researchers asked students why they did not report the incidents to law enforcement officers. The most commonly reported response — offered by more than half the students — was that they did not think the incident was serious enough to report. . . .

Researchers in one study asked students to distinguish between forced sexual assault and incapacitated sexual assault involving drugs and alcohol. . . . In the incapacitated group, 50 percent said they did not report the incident because they felt partially or fully responsible for what happened . . . .

Here, again, some observers will assume that they know better — that, no matter precisely what happened, the episode in question is always serious enough to report, and that the woman should never consider herself to be partly responsible. It would be rather hysterical to follow the advice (discussed below) that women across the nation need to call the police every time some unwanted man makes a failed attempt to kiss their cheek.

And yet that is the position taken in a publication produced by the U.S. White House (2014, pp. 7-8). That publication indicates that failure to report sexual assaults to police leaves the authorities unable to determine the extent of the problem. They need good police reports in order to know whether rape is a problem. That remark seems disingenuous, considering that the authors of that White House publication proceed to make confident assertions about the extent of the problem (see below) on the basis of data obtained by researchers through surveys rather than police records.

While there have undoubtedly been improvements in police handling of sexual violence reports, the fact remains that the legal system as a whole is a very clumsy instrument for resolution of intimate partner issues. It is not clear that women are always mistaken if (to cite a few other reasons offered by NVAWS participants) they decide not to report an instance of rape because they “did not want police or court involved,” because they “handled it myself,” because the “perpetrator was husband, family member, friend,” or because they “did not want perpetrator arrested.”

In rapes and in other matters as well, one might say to the White House and other presumptuous observers, don’t impose upon us the naive assumption that the authorities know best. Show us the reformed legal system that is capable of responding to the public’s needs for justice and law enforcement in real life, and then let us decide whether to second-guess the alternatives that people choose in lieu.

Simply put, it is difficult to get good data on the nature of the problem, and for a variety of reasons police records are not necessarily the first and best source. As becomes evident from the Methodology sections of some of these studies (e.g., CDC, 2011, p. 9), obtaining reliable information about such sensitive matters is a complex task that even veteran researchers struggle with. We will not soon see a nationwide state of affairs in which the average meek soul will readily trundle down to the police station to report a sour sexual experience.

Hence rape is, and for reasons good and bad will apparently remain, among the most underreported of all crimes (see Allen, 2007; Kilpatrick et al., 2007, pp. 2-3; Thomas, 2013). The Rape, Abuse & Incest National Network (RAINN) suggests that only 40% of rapes are reported to police, 10% lead to an arrest, 8% are prosecuted, 4% result in felony conviction, and 3% result in prison time.

Lifetime Prevalence of Rape of Adult Women in the U.S.

What is the prevalence of rape — that is, how many adult women have been raped, in total, at any point in their lives? Citing a 1998 survey, RAINN reports that 14.8% of American women have been raped.

By contrast, despite a sharp 20-year decline in rape rates (below), the White House (2014, p. 1) now says that nearly one in five American women (i.e., 20%) have been raped. The source cited for that proposition is CDC’s (2011, pp. 9, 100-105; 2014, p. 9) report on the National Intimate Partner and Sexual Violence Survey (which CDC oddly acronymizes as NISVS, 2010).

The NISVS survey was based on telephone calls to 9,970 women and 8,079 men, comprising less than one-third of the total number of people contacted (2011, p. 101). When so many people decline to talk about something, there is no way to know whether the ones who do participate are representative of the larger population. It could be, for example, that the people who are willing to sit and answer questions about sexual violence (average NISVS survey time: 25 minutes; see CDC, 2014, p. 8) are disproportionately likely to be those who have strong feelings on the matter. Those who did participate in the survey were more likely than the average American to be divorced or never married; women in those categories are at much higher risk of rape (below). Those who participate may also be more likely to have been trained to believe in surveys — may have been, that is, more exposed to college education. That, too, is true of these participants (i.e., higher average education), and it raises the question of whether their college exposure may have indoctrinated them, on matters related to sexual violence, in ways that are not typical of the general public. There is also the prospect that people who are willing to spend a chunk of time answering survey questions have more free time or, as in the case of these participants, lower than average income — raising the prospect that they are less protected from sexual violence risk factors, by career and lifestyle, and may therefore be more alarmed about the topic of rape. The impact of such factors can be profound; some subgroups are vulnerable to rates of rape much higher than that experienced by the general U.S. population. For example, the White House (2014, p. 11) cites a 2000 study for the proposition that 13% of homeless women had been raped in the previous year.

At the same time, CDC (2011, pp. 9-10) acknowledged that NISVS may have undercounted instances of sex coerced by psychological aggression. They did so because “there is little agreement about how to determine when psychologically aggressive behavior becomes abusive and can be classified as intimate partner violence.” The examples provided include “humiliation” and “limiting access to money.” A separate post discusses such behaviors further, from male as well as female perspectives. Briefly, one can imagine why there is little agreement among experts: people from different sexes and socioeconomic groups may indulge different forms of psychological pressure for their preferred ends within intimate relationships. Relational compromises do often have mercenary elements, entailing spoken or unspoken pressures and tacit agreements not to withhold money, for example, or sex; everybody is expected to carry their weight.

That said, one might have expected CDC to include at least those instances of psychological aggression that rise to the level of criminal conduct as expressed in standard definitions of rape. For example, it appears that CDC decided to overlook both “acting dangerous” (which could indicate a criminal threat of physical violence) and “humiliation” (which would probably not) merely because both happen to entail psychological rather than simply physical elements (as if there were no psychological aspects to other rape-related behaviors). It seems odd that CDC (2014, p. 19) would have lumped together, under the single heading of “psychological aggression,” the relatively mild offense of “[Making] decisions that should have been yours to make” and the very worrisome act of “[Saying] things like, ‘If I can’t have you then no one can.'”

These criticisms demonstrate an important fact about rape research. It can make good sense to try to figure out how many people, or what kinds of acts, will be affected by a law that is worded one way rather than another. It is another thing altogether for someone to sit back and draw arbitrary lines dividing up the enormously complex continuum of behaviors in relationships among mates, relatives, and acquaintances — which, as discussed below, is where the vast majority of rapes occur. The multifarious reasons cited for not reporting an incident to the police (above) tend to be an indication, not that women who do not report their experiences to the police are confused about acts that might be illegal under current law or disapproved in the academic consensus, but rather that the legislators and scholars are not doing very well at understanding and responding effectively to this tremendously complex realm of human experience. Simply put, these legislative and scholarly efforts do not necessarily work very well. As Gruber (2009, p. 655) puts it, “[A]ddressing sexualized violence through increasing the prosecutorial power of the state is an endeavor in which, at this particular moment, feminists should no longer enlist.”

In any case, in NISVS, CDC (2011, p. 18) estimated lifetime prevalence as follows: 12.3% of female survey participants reported experiencing completed forced penetration and 8.0% reported completed penetration facilitated by the woman’s indulgence of alcohol and/or drugs. CDC (p. 12) indicated that “victims of completed forced penetration and alcohol or drug facilitated penetration are included in each of these subtypes of rape but counted only once in the estimate of rape prevalence.” In other words, the 18.3% estimate of rape prevalence consists of the 12.3% who were raped by force, plus the 8.0% who were raped in connection with the victim’s consumption of alcohol or drugs, minus 2.0% for double-counting those who have experienced both. Rapes occurring in connection with alcohol and/or drugs can be especially controversial and difficult to interpret. For reasons discussed below, it is unlikely that that 8.0% would stand up to close inspection.

If the NISVS were revised to achieve accurate representation of the general public, and if its findings pertaining to alcohol and drugs were checked with more detailed interviews, it appears likely that it would report a lifetime prevalance of rape of no more than 16% of women. That is where other studies come out. For instance, Kilpatrick et al. (2007) concluded that 16.1% of American women had been raped at some point in their lives (p. 22). That figure, too, would likely fall if the women interviewed by Kilpatrick et al. (p. 14) had been representative of the general U.S. population in important regards specified by NISVS, including income and educational level. Kilpatrick et al. failed to indicate what proportion of the contacted women declined to participate in their survey, raising the prospect of nonrepresentativeness in that regard as well.

As another point of comparison, the NVAWS survey (CDC, 2006, p. 7) found that 14.8% of women were raped in their lifetimes. Data for this study were collected in 1995-1996 when, as already noted, rape rates were markedly higher. Here, again, response rates were not stated, so this study, too, may have been significantly nonrepresentative of the general public. It is particularly unlikely that NVAWS suffered from any serious undercounting of rapes among those who did participate: the study used thorough interviews featuring multiple questions to detect any possibility of sexual assault.

Notwithstanding the foregoing criticisms, both NISVS and the Kilpatrick study contributed some sense of the lifetime prevalence of rape of adult females in the United States. Taken together, a ballpark estimate would be that somewhere between 10% and 20% (i.e., one out of every five or ten) of such females claim to have been raped. Narrowing it down, the best guesses so far seem to hover around 14-16%, or one out of every six or seven women.

It bears emphasizing that, as discussed above, there are factors that could lift the rate (e.g., psychological coercion, in the CDC study), but it appears there would be greater pressure on the downside (e.g., use of more representative participants; verification of facts from the alleged rape situation; pronounced drops in rates of rape since the times of the older studies). Generally, it seems that the White House was not justified in asserting, as an established fact, that 20% of American women are raped at some point in their lives. No figure is established; but when it becomes necessary to present an estimate, 15% appears more accurate.

Incidence of Rape in a Single Recent Year

In addition to estimates of the lifetime chance of rape, various sources report on the rates of rape from year to year. Investigations of this question are subject to many of the caveats noted above. At the same time, the smaller and more recent timeframe seems likely to reduce somewhat the uncertainties and potential errors arising from long-term recollection, in lifetime rape studies like those discussed above.

CDC (2011, p. 18) estimates that, in the 12 months preceding the NISVS survey, 1.1% of adult American women experienced penetration facilitated by force, alcohol, and/or drugs. As discussed above, however, NISVS may have significantly overestimated the frequency of rape in the general population.

NVAWS (CDC, 2006, p. 7) offers a sharp contrast against NISVS. Despite their thorough questioning, NVAWS researchers found that only 0.3% of women had been raped in the previous 12 months. That figure is particularly remarkable because rape rates have decreased sharply since the time of the NVAWS data collection in 1995-1996. RAINN says, “Sexual assault has fallen by more than 50% in recent years.” Leinwand (2013) at USA Today concurs:

Reported rapes have fallen to the lowest level in 20 years as DNA evidence helps send more rapists to prison and victims are more willing to work with police and prosecutors, victims advocates and crime researchers say.

In addition, she says, some of those changes are creditable to the Violence Against Women Act (1994) and the institution of public awareness campaigns in high schools and colleges in the 1970s and 1980s.

The 0.3% figure produced by NVAWS does not prove that NISVS overstated rapes, but it certainly does raise the question. Other studies have likewise produced figures lower than those of NISVS. For instance, Kilpatrick et al. (2007, p. 4) estimated 0.74%, and cited the older NWS study for an estimate of 0.71%.

As indicated in my previous post, the Federal Bureau of Investigation (FBI) switched to a broader and more contemporary definition of rape as of 2013. It remains to be seen what trends may emerge from that new definition. Historical FBI data document, in general terms, a drop similar to the one reported by BJS. The FBI estimates 52.9 rapes per 100,000 female inhabitants in 2012, for a rate of about 0.05% (i.e., five per ten thousand) per year, using the FBI’s old definition of rape.

BJS (2013, p. 1) says, “Between 1995 and 2010, the rate of completed rape or sexual assault declined from 3.6 per 1,000 females to 1.1 per 1,000.” Those figures were obtained, not from law enforcement records, but from the BJS National Crime Victimization Survey. As noted in a previous post, sexual assault is a much broader concept than rape; rape would constitute only a fraction of that figure of 0.11%.

To summarize, estimates of the annual incidence of rape among adult American women range downward from 110 per ten thousand (i.e., 1.1%) to somewhere around five per ten thousand (i.e., 0.05%). Several studies have reached values in the range of 0.3% to 0.7%. For purposes of discussion, it may be reasonable to adopt an estimate that about 0.5% of American women (i.e., five per thousand) are raped each year.

Age Distribution of Rapes

Using data from 1995-1996, NVAWS (CDC, 2006, p. 18) found that 54% of women who had ever been raped were first raped before age 18. As with other findings from the 1990s, this rate appears to have declined. CDC (2011, p. 25) states that only 42.2% of raped women were first raped before age 18. Thus, in place of the White House (2014, p. 9) claim that “nearly half of female survivors were raped before they were 18,” it could be more accurate to observe that, in recent years, rape of female children and adolescents has continued to drop further below the 50% mark.

BJS (2013, p. 3) suggests that 43.2% of rape victims are under 18 years old, but that calculation does not include rapes before age 12. CDC finds that 12.3% of females who have ever been forcibly raped (i.e., about 2% of all females) were first raped before age 11. That is, BJS appears to imply that CDC is slightly understating the percentage of rape victims who were first raped before turning 18. So the recent percentage of females who are first raped before age 18 may be around 45%.

Note that these calculations are focused on women who have been raped, as distinct from all women. Splitting the difference between those CDC and BJS calculations, suppose that 43% of first-time rape victims are under 18. According to the discussion of prevalence (above), only about 15% of all women have ever been raped, at any age. So about 6.5% of all women (i.e., 43% of 15%) will have been raped by age 18.

This means that 8.5% of all women (i.e., 15% – 6.5%) will have their first (and, as noted above, probably their only) experience of forcible rape at age 18 or later. In other words, if a woman makes it to age 18 without being raped, there is a likelihood of around 92% that she never will be raped.

To some extent, these calculations suggest that youth and inexperience can be dangerous. CDC (2011, p. 25) indicates that the eight-year period from age 11 to age 17 accounts for 30% of all first experiences of rape, whereas the entire second half of life and more — the period of, on average, about 40 years of middle and old age, beginning at age 35 — accounts for only about 6% of all first-time rapes.

This is what one might expect. Starting in one’s twenties, older women tend to find themselves married, working, busy with kids, or otherwise unlikely to be living the social lives they may have indulged at a younger age. They are more experienced and less likely to be meeting as many men, engaging in risky behaviors, or making foolish mistakes.

On a related point, BJS (2013, p. 3) finds that women who are unmarried, divorced, or separated at the time of the survey are roughly six times more likely to have been raped than are married or widowed women. Note also that CDC (2011, p. 26) finds that women who were raped as minors are 2.5 times more likely to be raped again as adults, suggesting a possible need for interventions focused on that subgroup. A similar pattern appears in NVAWS (2006, p. 20).

For various reasons, then, it appears that more than nine out of ten of the women who reach age 18 without being raped never will be. And if they reach age 35 without being raped, the odds in their favor are more like 99 out of 100. Of course, if rape rates continue to decline in coming years, even these figures may err on the pessimistic side.

Rape in College

The White House (2014, p. 6) says, “One in five women is sexually assaulted while in college.” The sources for that assertion are The Campus Sexual Assault (CSA) Study (U.S. Department of Justice, 2007) and a discussion of that study in a 2009 article. Data for the CSA Study were gathered in the winter of 2005-2006. It is not clear why the White House treated data that were nearly a decade old as though they reported current facts, given the profound drop in rapes taking place over the past two decades (above).

As noted by The Washington Post, the data for this study came from just two large public universities (2007, p. 3-1), and thus were probably not representative of women at all sorts of two- and four-year colleges and universities. Data were gathered by an online survey that was apparently open, in fact although not in intention, to anyone who might care to cast one or more votes, regardless of who they might be. The total number of participants constituted only about 43% of the number of women invited to participate (see 2009, p. 645). Thus, it could not be demonstrated that results were representative even of the women in those two universities. The authors themselves warned against any attempt to apply their findings to all universities (2009, p. 645). In citing the CSA Study as a definitive indication of the rape situation nationwide, the White House falsified what that study said.

The CSA Study defined sexual assault as consisting of either rape or sexual battery. The study used a definition of rape largely consistent with the predominant use presented in my previous post — “unwanted sexual penetration (vaginal, anal, oral, or object penetration by an offender) achieved either through physical force, threat of force, or incapacitation of the victim” (2007, p. 1-2). The study defined sexual battery as “sexual assault that entailed sexual touching” without rape (2007, p. xi; 2009, p. 640). In the definition of sexual touching, the authors included “forced kissing, touching of private parts, grabbing, fondling, rubbing up against you in a sexual way, even if it is over your clothes” (2009, p. 646). This was a very broad definition, as explored in the next few paragraphs.

For one thing, it appears that the study’s authors equated “forced” with “unwanted.” Hence, a man who kissed a woman whom he mistakenly thought wanted to be kissed (and similarly with other touching) would be deemed to have committed a forced sexual battery, even if she did not make up her mind about it until afterwards. As the study admits, such behaviors “arise in common college social situations” (p. xviii). It appears, in other words, that the Obama Administration takes a stand on what ordinary, non-assaultive people are allowed to do when they go out on a date — that, among other things, a man must ask a woman’s permission (and vice versa) before any act of kissing or touching is allowed to take place. Indeed, the terms are not restricted to behavior among strangers; apparently it would also be necessary to verify such permission even when married, as it is not necessarily safe for the parties (men, especially) to infer consent.

The CSA Study implausibly reports that experiences of sexual battery, so defined, were significantly less common than experiences of rape (2007, p. 5-2). Since unwelcome attempts at kissing and touching do occur quite frequently — much more frequently than rape — in the fumbling guesswork of various dating situations, it seems that participants in the CSA Study must have been deciding which episodes to report, and reporting only a fraction of their actual experiences. An unknown but probably very large number of experiences of being kissed or touched in various ways by undesirable dates and acquaintances were apparently not reported.

Similarly, many men and women have no doubt experienced instances of mediocre and bad sex with persons whom they did not always want in their lives, sometimes doing so for quasi-coercive reasons (e.g., “I don’t want her to think I don’t find her attractive”; “the deal is that I put out and he pays out”), but do not think of or report those experiences when asked about coerced sex qualifying as rape. Small wonder that Sommers (2011) would say, “Research on sexual assault is notoriously hard to conduct, and the studies are wildly inconsistent.” Consistent with remarks made earlier in this post, Sommers appears to advocate research that would leave it up to the participants to decide whether, in fact, they have been assaulted, rather than allowing researchers to impose their own definitions on myriad real-life situations in which they were not present.

The White House claim that one in five women is assaulted in college does not cite a specific page in the CSA Study. The claim appears to refer to the finding that 19.0% of women “reported being a victim of attempted or completed sexual assault of any type . . . since entering college” (2007, p. 5-1). By definition, being a victim of attempted sexual assault is very different from being a victim of completed sexual assault. The CSA Study clarifies that only 13.7% were victims of completed sexual assault (2007, p. 5-2). In this regard, the White House made an obviously false statement that greatly exaggerated the rate at which women are, in fact, sexually assaulted in college.

As just noted, the CSA Study expanded the concept of completed sexual assault to include a mere ill-timed kiss. But what about the “attempted” dimension? Evidently you become guilty of attempted sexual assault, for purposes of the White House’s statistics, if you tried to kiss someone but s/he turned aside, or if s/he held onto your hand to prevent you from touching or caressing anything — or even if s/he was the less gentle sort, and kicked you, pepper-sprayed you, hit you with a weapon, or had his/her friend knock you down, so as to make sure you got the message.

There are some other problems with certain percentage calculations in the CSA Study. This paragraph discusses those problems, for readers interested in specifics. Briefly, the authors of the CSA Study stated that 3.4% of survey participants had been forcibly raped since entering college and 8.5% had been raped while incapacitated (2007, p. 5-2). The study defined incapacitation as including any condition in which “a victim is unable to provide consent or stop what is happening,” including being unconscious, drugged, drunk, or asleep” (2007, p. ix). While the authors evidently intended to make those two options mutually exclusive with respect to a single event, it is not clear whether the online survey prevented participants from describing a single event in both ways. The figures just cited, 3.4% and 8.5%, do not add to the conclusion that 11.9% of women experienced one kind of rape or the other, not only because there may have been some double-counting as just indicated, but also because the study focused on numbers of women, not numbers of rapes. That is, some women evidently reported both kinds of rapes and/or sexual assaults: the report indicates that 4.7% of women experienced physical forced sexual assault and 11.1% experienced incapacitated sexual assault — but, as noted above, that only 13.7% (i.e., not 4.7% + 11.1% = 15.8%) experienced any kind of sexual assault. The authors bizarrely failed to provide detailed numbers or even a table of percentages that would add to 100%, so as to permit a straightforward calculation of the percentages of women claiming to have been raped (by force and by incapacity combined). Based on the limited information provided, apparently the percentage could be up to 2.1% (i.e., 15.8% – 13.7%) less than the 11.9% combined total noted above.

As suggested by the title of the 2009 article, the authors of the CSA Study were particularly interested in the problem of incapacity. The study distinguished rapes that were facilitated by the woman’s voluntary or excessive use of alcohol and/or drugs from rapes that were facilitated by someone’s act of drugging the woman without her knowledge (2009, p. 639). Here, again, despite their focus on such matters, the authors failed to provide specifics. Based on the scant detail provided, one can guess that rapes occurring in situations of voluntary or excessive alcohol or drug use may have been about four times more common than rapes occurring where the woman suspected that she might have been drugged, and about 13 times more common than rapes occurring where the woman was certain that she had been drugged (2009, p. 641). That is, one might consider that, as Sommers (2011) points out, the authors of the CSA Study surely overreached in assuming that “an intoxicated person cannot legally consent to sexual contact” (2007, p. 6-5) — that, in other words, sex with an intoxicated woman is rape. In Sommers’s words, “If sexual intimacy under the influence of alcohol is by definition assault, then a significant percentage of sexual intercourse throughout the world and down the ages qualifies as crime.”

The National Institute of Justice (NIJ, 2008) offers some perspective on campus sexual assault, as of the time of the CSA Study writeups:

The number of reported forcible sex offenses on American campuses has declined in recent years, according to crime statistics compiled by the U.S. Department of Education. . . .

Unfortunately, researchers have been unable to determine the precise incidence of sexual assault on American campuses because the incidence found depends on how the questions are worded and the context of the survey. For example, researchers did two parallel surveys of American college women during the same time and came up with very different results. . . . [T]he percentage of the sample that reported experiencing a completed rape in one study was 11 times the percentage in the other study. . . .

[T]he often-quoted statistic that one in four American college women will be raped during her college years is not supported by the scientific evidence.

The CSA Study is not completely ridiculous. It could have been written better, and it certainly incorporates some dubious beliefs, but it still comprises a substantial amount of informative research. What is particularly objectionable is the use that the White House made of it, against its authors’ own warnings.

In light of the factors just discussed and the earlier remarks on shared responsibility, it tentatively appears that the CSA Study suggests that, circa 2005, about 3% to 4% of women claimed to have been raped by force or coercion while in college, and another 7% claimed to have experienced intercourse in situations involving alcohol and/or drugs that vary from outright rape of an incapacitated woman to ambiguously consensual or later-regretted sex that might not have happened without the influence of such substances, and that might not have been categorized as rape without the aid of the extreme views incorporated into the CSA Study.

For  purposes of comparison against that estimate of a 3-4% incidence of rape while in college, one might consider the foregoing section of this post regarding the age distribution of rape. That section indicated that only about 8% of women have their first experience of rape at any time in their lives after age 18, and that few will be raped more than once. Only a fraction of women spend four years in college. Those facts could suggest that perhaps 4% of women experience, in colleges and universities, the actual crime of rape as defined previously. Even that relatively low percentage would considerably exceed the rates suggested by some research (see Kitchens, 2013; Department of Education, 2012). But for present purposes, an impression that less than one in 25 women will be raped during four years in college seems adequate to convey a justifiable counterpoint to exaggerations from the White House and elsewhere.

Data on Perpetrators

The National Intimate Partner Violence Survey (NIPVS) (CDC, 2011, p. 22) estimates that, over their lifetimes, the large majority of raped women are raped by people whom they know. CDC breaks that general category of perpetrator down into several subgroups: current or former intimate partners (referred to here as simply “partners”), family members, persons in position of authority (“power figures”), and acquaintances. The National Violence Against Women Survey (NVAWS) (CDC, 2006, p. 25) found that 94% of women raped by partners were first raped while they were still together — that, in other words, rape was rarely initiated as a new behavior after a couple split up.

It would have been helpful if CDC had specified the numbers of perpetrators, in NIPVS, since that is the topic at hand in this portion of its presentation. Unfortunately, CDC chose instead to orient its report around the numbers of victims. This treatment is consistent with the sometimes odd focus on victims to the exclusion of all else, but in this regard it leads to mystifying results.

Specifically, CDC says that, of the victims of forcible rape, 51.1% were raped by partners, 12.5% by family members, 2.5% by power figures, 40.8% by acquaintances, and 13.8% by strangers. That adds up to 120.7%. CDC explains that the excess over 100% is due to the existence of multiple perpetrators. Apparently this implies that, on average, for every 10 women raped, there are about 12 rapists — some in multiple-rapist scenarios, but presumably most serially: the victim was raped at different times by different people. There would be some problems with that interpretation: for instance, NVAWS (CDC, 2006, p. 12) found that, over their lifetimes, 78.2% of female rape victims were raped by just one person, 13.5% were raped by two people, and 8.3% were raped by three or more people. These figures are similar but not identical to those found in the NISVS study (CDC, 2011, p. 24): 71.2% by one, 16.4% by two, and 12.4% by more than two. CDC seems to indicate that, among perpetrators whom victims know, the ratio is about 5:4:1: five are partners, four are acquaintances, and one is a family member. For rapes facilitated by alcohol and/or drugs rather than force, the ratio is more like 6:7:1, with only 9.6% committed by strangers.

One might observe, in passing, that rapes by acquaintances, relatives, or partners arise in circumstances that can vary greatly among themselves, and that also tend to vary considerably from the kinds of circumstances in which stranger rapes occur. In this sense, lumping these various crimes together under the single heading of “rape,” based on the victim’s physical experience, could be somewhat like lumping together murder, manslaughter, being killed by police or by an opposing army, and assisted suicide under the single word “homicide.”

As another philosophical observation, it was interesting to see, in NVAWS (CDC, 2006, p. 17), that, as of 1995-1996, about 22% of adult females born at any time after World War II had been raped at some point in their lives, whereas only 7% of adult females born before 1926 had ever been raped. The NVAWS (p. 19) authors also observed that the risk of a female’s being raped before age 17 had risen significantly since the 1930s. The authors suggested that this change may have been due to reluctance to admit victimization in older generations. Another possibility is that social upheaval commencing in the 1960s may have created a society far less protective of females than that which had gone before.

Consistent with its focus on the victim, CDC (2011) does not provide data on ages, races, or other characteristics of perpetrators. Reliable data may be hard to obtain, given reportedly low rates of reporting, arrest, and conviction. BJS (2013, p. 5) offers summary data based on victims’ perceptions of perpetrator characteristics. These perceptions indicate that only 11% of criminal sexual assaults included possession of an identifiable weapon; that 24% of perpetrators were perceived to be under 21, and 48% were perceived to be 30 or older; that 57% were white, 27% were black, and 8% were of unknown race; and that alcohol and/or drug use was evident in only 39% of cases. NVAWS (2006, pp. 11, 26) provides further detail on these and related questions, including the potentially surprising finding that only 68% of rapes involved the penetration of vagina (as distinct from mouth or anus) by penis (as distinct from fingers, tongue, or object).

Finally, according to the National Institute of Justice (NIJ, 2008), “Experts speculate that rape and other sexual assaults may be like other crimes inasmuch as a relatively small number of people commit serious crimes.” For example, Lisak and Miller (2002, p. 78) found that a set of 76 repeat rapists — that is, a mere 4% of a sample of 1,882 male college students — accounted for 35% of all violent acts admitted by those 1,882 men. The acts of violence for which those 76 claimed responsibility included 439 rapes. Within that group of 76, a subgroup of 11 perpetrators claimed responsibility for between nine and 50 rapes each. Such reports would call for further investigation into,  among other things, the status (e.g., partner, stranger) of such serial perpetrators vis-à-vis those victims.

For further reading, the University of Michigan offers a webpage with citations to numerous articles on perpetrators. At this writing, unfortunately, it appears that page hasn’t been updated since sometime around 2007.


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