Sex offender statisctics, arrest data, and other demographic information

By Arizona Rape and Sexual Assault Surveillance Project

University of Arizona, University of Arizona Prevention Center

Official police statistics document how many sexual assaults have been reported to the police. In the United States, forcible rape is an index crime collected by the Federal Bureau of Investigations (FBI) through the Uniform Crime Reporting (UCR) Program and published annually in Crime in the United States. Seven crime categories - murder and nonnegligent manslaughter, forcible rape, robbery, aggravated assault, burglary, larceny-theft, and motor vehicle theft – are collectively known as the Crime Index. The official purpose of tracking the Crime Index is to "measure the trend and distribution of crime in the United States" (Maguire and Pastore 1996, p. 325). However, the data are most reliable as indicators of the functioning of law enforcement.

Forcible rape is defined as, "The carnal knowledge of a female forcibly and against her will. Included are rapes by force and attempts or assaults to rape. Statutory offenses (no force used--victim under age of consent) are excluded" (Maguire and Pastore 1996, p. 644). This definition only includes rape as the penetration of a woman's vagina by a man's penis. Penetration of other orifices by other body parts or objects is excluded, as is penetration of a man or by a woman.

Only founded reports are counted in the UCR Program. First, a crime must come to the attention of the police by being reported or by the police seeing the crime occur. Then, the report must be considered founded. Reports not believed or considered impossible to prove by an officer are considered unfounded and will not be officially counted.

The current implementation of the UCR Program collects only aggregate data from police departments around the country. The National Incident-Based Reporting System (NIBRS) is being piloted in several states. NIBRS will provide more detailed crime incident-based data as it is phased in. Some preliminary data is available. However, Arizona is not one of the pilot states and there is no scheduled inclusion date at this time.


It is estimated that 102,096 forcible rapes, 39.2 per 100,000 population, were known to the police in the United States in 1994. In 1994, Arizona ranked 25th as a state with a forcible rape rate of 36.0 per 100,000 population (Maguire and Pastore 1996, p. 336), representing 1465 forcible rapes among a population of 4,075,000 (Maguire and Pastore 1996, p. 326). Table 6 above shows the offenses known to the police in cities over 100,000 people in Arizona. In 1994, 29,791 people, or 14.3 per 100,000 population, were arrested for forcible rape in the United States (Maguire and Pastore 1996, p. 396). In Arizona, 246 people were arrested for forcible rape, or 6.3 per 100,000 population (Maguire and Pastore 1996, p. 398), in 1994. In 1994, 178 defendants were convicted of rape in U.S. District Courts (Maguire and Pastore 1996, p. 468), 87.1% of whom were sentenced to prison with an average sentence length of 68.4 months (Maguire and Pastore 1996, p. 473). As of December 31, 1994, 430 prisoners in the custody of U.S. military authorities had been convicted of rape (Maguire and Pastore 1996, p. 587). Arizona was one of seven states not responding to a 1995 national survey on sex offender housing (Maguire and Pastore 1996, p. 579).

Critical Assessment

The major advantage that using the UCR Program as a source of sexual assault surveillance data is its relatively low cost to users. The UCR program is a criminal justice program generating public data that will continue to be funded for the foreseeable future. The only financial costs incurred in accessing this data are personnel wages and telephone bills. However, the data obtained is not suitable as surveillance data. Several of the biases encountered in UCR data are enumerated below.

Most sexual assault statutes in the United States under which perpetrators can be arrested are much more general than forcible rape, including penetration of any orifice of a man or a woman by any object. Sexual assault under the Arizona Revised Statutes is defined as, "A person commits sexual assault by intentionally or knowingly engaging in sexual intercourse or oral sexual contact with any person without consent of such person," where sexual intercourse is, "penetration into the penis, vulva or anus by any part of the body or by any object or masturbatory contact with the penis or the vulva" (Arizona Revised Statutes (ARS) Criminal Code Chapter 14 Section 13-1406, Sexual Assault). The numbers reported to the UCR Program for forcible rape statistics depends in part upon their staffing. Those departments with staff and resources devoted to statistical record keeping can afford to take the time to distinguish cases of forcible rape from cases of sexual assault. Others do not have as many resources and report sexual assaults as forcible rapes. Reporting sexual assaults as forcible rapes over reports the number of forcible rapes.

A similar problem occurs with rapes of children. The definition of forcible rape does not limit the age range of those victimized. However, most perpetrators whose victims are children will be prosecuted as child molesters rather than rapists. The age distribution of the victims is unknown. This reporting behavior will tend to under report the number of victims.

Although the definition of forcible rape excludes men as victims, men are included in the denominator of the official forcible rape rate calculation leading to two distinct problems. 1) Rapes of males are not officially counted, and 2) the rate of victimization appears to be half of what it is among those most at risk. Although rapes of men are rare, they do occur and should not be ignored. The standard answer I received when inquiring of police departments as to how male rape is counted was to be told to call the prisons. It is not surprising that men are much less likely to report sexual victimization when it is rare and the only place male rape is expected to occur is in a penal institution. However, despite the undercounting of victimization of men, women are much more likely to be raped. The inclusion of men in the denominator of the rape rate calculation when they are not included in the numerator diminishes the rate by 50% because approximately half of the population of the United States is male. Estimates of the rate of forcible rape as reported to the police should be twice as large as they currently are.

In addition to the internal validity concerns raised by definitional problems, the reliability of police statistics is suspect because rape is one of the most underreported of all the index crimes. According to the National Crime Victimization Survey, 32% of victims of rape or sexual assault reported to a law enforcement agency in 1994 and 1995 (Greenfeld 1997). The most common reason for reporting to the police is to prevent further crimes by the perpetrator. However, most victims are reluctant to report assaults to the police for a number of reasons. The most common reason for not reporting to the police is that it was considered a personal matter. Other reasons for not reporting to the police include believing that they were responsible for the assault, being afraid of the social consequences of identifying oneself as a rape victim, believing that the police will be ineffectual in investigating the crime, and not wanting to become involved in what they believe will be a long and complicated legal process. All of the above reduce the likelihood that a sexual assault will be reported to the police. A victim may also not report to the police because, although their sexual experience may fit the definition of rape, they believe that they simply had a bad sexual experience without recognizing that a crime had occurred. The number of rapes occurring in the community can easily be an order of magnitude or more larger than the number known to the police. The National Women’s Study found that 84% of rape victims do not report to law enforcement (National Victim Center and Crime Victim Research and Treatment Center 1992). In the state of Arizona, the number of calls received by rape crisis hotlines is about 10 times the number of sexual assaults known to the police.

The one year reference period of the UCR statistics do not reflect the reality that victims may delay seeking treatment and/or require treatment for a long period of time. For example, approximately 50% of the clients seeking treatment at the Tucson Rape Crisis Center are adults molested as children. The UCR statistics do not address the longitudinal nature of reporting and treating sexual assault.

Statistics on the prosecution of rape underestimate the number of rapists because prosecutions are generally classified by the most serious offense. For example, crimes involving victims that were both raped and murdered will be classified as murders. At every level of the criminal justice process, the number of sexual assaults is underestimated and the further along one goes in the legal process the larger the magnitude of the problem.