Understanding National Rape Statistics

Dean Kilpatrick and Jenna McCauley With contributions from Grace Mattern

Policy makers and those who serve sexual violence victims/survivors need accurate information about violence against women to document the extent of the problem and to develop effective public policy, criminal justice, public health, and prevention programming. Those who seek such information are often frustrated because they are confronted with a confusing and often conflicting array of sexual violence statistics that make it difficult to understand the extent of the problem and whether it is getting better, staying the same or getting worse. The primary purpose of this paper is to provide an overview of how estimates of sexual violence in the United States are produced, with particular emphasis on major sources of rape statistics at the national level. Although having good estimates of rape at the local and state levels would be particularly valuable for local and state programs, such information is generally lacking, so we will focus this review primarily on rape statistics at a national level. Also, we will focus primarily on the crime of rape as opposed to other types of sexual violence. We will address rape among women and female children, as these cases compose the majority of rapes and therefore constitute the large majority of national estimates. Information contained in this report is meant for educative purposes, to either stand alone or be incorporated into broader training and education programming, and may prove useful to an array of advocates in the arena of prevention of violence against women.

As we will describe, rape statistics are generated from two sources: (1) cases reported to law enforcement and (2) victimization surveys. Victimization surveys were developed by criminologists in the late 1960s to measure crimes including those that are not reported to the police (e.g., Skogan, 1981; Sparks, 1982). They involve asking people a series of screening questions designed to prompt respondents to remember and disclose various types of crime that they may have experienced. This method gathers detailed information about any crimes disclosed including whether they were reported to law enforcement. We think it is useful for consumers of rape statistics to ask themselves the following questions as they consider each source:

Definitions and Terminology

Federal Criminal Code Definition of Rape

It is important to note that despite the traditional understanding that states had primary jurisdiction in the matter of violent crimes, recent years have seen an expansion of the Federal Criminal Code to cover many violent crimes, including rape. Although the Federal Criminal Code of 1986 (Title 18, Chapter 109A, Sections 2241-2233) does not explicitly use the term ""rape,"" aggravated sexual abuse is referenced and two types are identified: (1) aggravated sexual abuse by force or threat of force, and (2) aggravated sexual abuse by other means. Aggravated sexual abuse by force or threat of force is defined within the code as follows: when a person knowingly causes another person to engage in a sexual act, or attempts to do so, by using force against that person, or by threatening or placing that person in fear that they will be subjected to death, serious bodily injury or kidnapping. Aggravated sexual abuse by other means is defined as follows: when a person knowingly renders another person unconscious and thereby engages in a sexual act with that other person; or administers to another person by force or threat of force without the knowledge or permission of that person, a drug, intoxicant, or similar substance and thereby, (a) substantially impairs the ability of that person to appraise or control conduct and (b) engages in a sexual act with that person.

This definition has several important implications for what should be included in the assessment of rape. First, this definition includes more than just unwanted penile penetration of the vagina, and recognizes that not all perpetrators are male, not all victims are female, and that rape may include other forms of penetration, such as oral and/or anal. Second, the definition acknowledges that unwanted sexual penetration should be recognized in both the instance of being obtained by force/threat of force and the instance of drug-alcohol facilitation/incapacitation. Third, the definition highlights that statutory rape (i.e., any type of non-forcible sexual penetration with a child) is a serious federal offense and should be measured in national surveys in order to capture the full scope of the problem of rape. As noted during the discussion of individual national surveys that estimate the burden of rape, not all assessments of rape include the diverse range of unwanted sexual experiences that are defined as rape by the Federal Criminal Code.

Methods of Measurement of Rape Prevalence

Several general statistics are provided by national data on rape, and it is helpful to make distinctions in terminology prior to a review of the findings from individual studies. It is important to note that there is a distinction between rape cases and rape victims . A single rape victim may (and often does) have experienced multiple rape cases. Similarly, there is an important distinction to be made between rape prevalence and rape incidence . Prevalence refers to the proportion or percent of the population that has been raped at least once in a specific period of time. ""Lifetime"" and ""past-year"" are common time frames used in the assessment of prevalence. Incidence refers to the number of new cases of rape that occur in a specified period of time. Incidence is most often expressed as a victimization rate, or number of incidents per given number of people. Also worth noting is the difference between ""reported (to authorities)"" and ""unreported"" cases of rape. Given that a majority of rape cases, 84% by recent national estimates (Kilpatrick et al., 2007), are not reported to the police, there is a notable difference between rape estimates based on cases reported to law enforcement versus unreported cases.

When thinking of the differences between incidence rates, past-year prevalence, and lifetime prevalence, it is important to consider that these estimates can serve different functions for the reader. For instance, if a rape crisis center is interested in how many women they can reasonably expect to serve in a given year, past year prevalence (a person-based estimate) may be most useful. However, one could also extrapolate from past year victimization rates by applying these to the current population of their community. For example, if an annual victimization incidence rate of 1.8 is applied to a community with 100,000 women, the local crisis center could expect that approximately 1,800 rape cases will occur in their area in that year. Alternatively, law enforcement agencies or victim advocate agencies may be most interested in the incidence of reported rape cases, as this would be most closely related to the size of their population served. Thirdly, mental health providers in a given community may be interested in the community mental health burden of rape, a question best addressed using lifetime prevalence data on rape. While the different ways of measuring rape may make the data seem somewhat confusing, differing forms of measuring rape are necessary to address differing needs of service providers.

Key Terminology

ï  Carnal Knowledge: (see UCR definition of rape); the act of a man having sexual bodily connections with a woman; sexual intercourse.

ï  Drug-Alcohol Facilitated Rape: an incident in which the perpetrator deliberately gives the victim drugs or alcohol without her permission in an attempt to get her high or drunk and then commits an unwanted sexual act against her involving oral, anal, or vaginal penetration.

ï  Forcible Rape: unwanted sexual act involving oral, anal, or vaginal penetration that occurs as a result of the perpetrator's use or threat of use of force.

ï  Incapacitated Rape: unwanted sexual act involving oral, anal, or vaginal penetration that occurs after the victim voluntarily uses alcohol or drugs and is passed out or awake but too drunk or high to consent or control her behavior.

ï  Incest: non-forcible sexual intercourse between persons who are related to each other within the degrees wherein marriage is prohibited by law.

ï  Incidence: an estimate that is based on the number of cases of rape occurring in a given period of time; usually expressed as a victimization/rape rate; women with multiple victimizations would count for each of their multiple victimizations in this analysis.

ï  Lifetime Prevalence: the proportion of the population that has ever been raped.

ï  Past Year Prevalence: the proportion of the population that was victimized during the past year; most often based on prevalence of persons.

ï  Population Estimates: calculated by multiplying prevalence data by national estimates (most often US Census data) of the total population from which the sample was drawn.

ï  Prevalence of Persons: the proportion of the population that was victimized at least once during a given time; women with multiple victimizations would only count as one unit in this analysis.

ï  Random Digit Dialing Method: a sampling method that involves random generation of landline telephone numbers within a given exchange, to be called for survey participation. Random digit dialing methods give access to unlisted telephone numbers.

ï  Statutory Rape: any type of non-forcible sexual penetration with a child.

  Sources and Estimates

The major sources of U.S. prevalence data on rape included in this paper are summarized below:

Uniform Crime Reports (UCR)

The UCR is a publication of the Federal Bureau of Investigation (FBI) that estimates the number of cases of forcible rape and attempted forcible rape as well as other violent crimes that are reported to participating law enforcement agencies across the U.S. Reports are issued annually and data from 2007 are reported below.

Who was Included: In order to be included in the UCR, a rape has to be reported to law enforcement. Participating law enforcement agencies compile information on relevant cases (those meeting the definition below) and send it either directly to the FBI or to an agency at the state level that processes cases and then sends them to the FBI. Unfounded cases of rape, cases that (according to federal reporting requirements) are presumed to be false or without basis upon investigation, are not included in the data. Only rapes or attempted rapes of women are included in the report. According to the FBI, approximately 94.6% of the U.S. population resides in jurisdictions that report to the UCR program. The UCR data include 95.7% of the population in metropolitan statistical areas, 88% of the population in cities outside metropolitan areas, and 90% of the population in non-metropolitan counties. The sample includes girls and women of all ages.

What was Measured: Forcible rape is defined in the FBI's Uniform Crime Reporting Program as ""the carnal knowledge of a female forcibly and against her will."" Carnal knowledge is defined as ""the act of a man having sexual bodily connections with a woman; sexual intercourse."" Carnal knowledge applies only to penetration of the vagina by the penis, no matter how slight the penetration. Assaults and attempts to commit rape by force or threat of force are also included. Note that oral and anal penetration is not assessed.

Rapes by means of the victim's intoxication, or inability to consent, are not included in this assessment. Statutory rape (without force) and other sex offenses, such as incest, are not included. However, a rape by force involving a female victim and perpetrated by a family member is counted as a forcible rape, not an act of incest. The FBI manually calculated the 2007 rate of females raped based on the national female population provided by the U.S. Census Bureau.

Findings: Based on data from 2007, an estimated 90,427 founded cases of forcible rape or attempted forcible rape were reported, with 92.2 percent of these cases being rape offenses, and assault to rape attempts accounting for the remaining 7.8 percent of reported cases. This equates to a forcible rape rate of 3 cases per 10,000 women.

National Crime Victimization Survey (NCVS)

The NCVS is conducted by the U.S. Department of Justice, Office of Justice Programs and housed in the Bureau of Justice Statistics. Twice annually (every six months), the NCVS collects detailed information on the frequency and nature of rape cases, regardless of whether these cases were reported to the police. Reports are issued annually and data from 2007 are reported here.

Who was Included: The U.S. Census Bureau personnel interview, via telephone (excepting the first and fifth interviews which are face-to-face), household members in a nationally representative sample of approximately 73,600 men and women aged 12 and older from 41,500 households. New households are rotated into the sample on an ongoing basis and, once selected, a household remains in the sample for three years. The NCVS is currently administered in both English and Spanish versions.

What was Measured: Questions on the survey assess victim information (including age, sex, race, ethnicity, marital status, income, and educational level), offender information (including sex, race, approximate age, and victim-offender relationship), and information regarding the crime itself (time and place of occurrence, use of weapons, nature of injury, and economic consequences). All items assessed are bounded within the year of assessment. Two items assess rape experiences for both men and women. They are:

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