Every day, law enforcement agencies rely upon detailed crime incident data to make tactical and operational decisions about how best to deploy resources and combat crime in their communities. These same data, when pulled together from thousands of police organizations, can improve the understanding of the nature and scope of criminal offending and victimization and, in turn, inform public policy and crime prevention strategies. The FBI’s National Incident-Based Reporting System (NIBRS) is the U.S. federal system that collects detailed data about crimes known to law enforcement. Currently, more than 6,900 agencies across 33 states contribute their crime incident data to the system. In January 2021, NIBRS will become the exclusive reporting standard for the FBI’s Uniform Crime Reporting (UCR) Program.

The information herein is from an analysis of NIBRS data on rape and sexual assault victimizations in 2015 as reported by law enforcement organizations in 15 states.¹ The analysis is de-signed to illustrate some of the unique indicators of crime that agencies can generate through NIBRS; indicators that law enforcement can use to demonstrate their commitment to transparency and communication with local residents, businesses, the media, and other stakeholders. Better crime data also provide law enforcement with a powerful tool to identify and to dispel myths and misconceptions about crime. For instance, NIBRS data show that most sexual assault victims are juveniles, not adults, and that the overwhelming majority of sexual assault victimizations are committed by someone the victim knows.

Using the federal NIBRS data can be daunting—the files are large and the incident information is separated into individual incident segments that must be linked. The Bureau of Justice Statistics developed a set of NIBRS extract files that merge these data segments together, so that all of the information for each incident is contained in one file. Most crime analysts and other individuals with a bit of database management knowledge could use readily available software—including free programs such as R—to extract a subset of NIBRS data for analysis. Most of the findings presented here as examples can be generated through a relatively simple Excel query on a subset of data on violent victimizations from the NIBRS victim extract file. In addition, the FBI allows the public to view and download NIBRS data by state and by year through their Crime Data Explorer.²

Victims of Sexual Violence

As law enforcement leaders know, corroborated by the summary-based data submissions to the FBI’s UCR Program every year, rape and sexual assault account for about one out of every five violent crimes reported to the police.³ An analysis of reported violent victimizations from NIBRS data shows a similar percentage (Figure 1). However, those summary-based counts of violence cannot provide much additional information about those sexual assault victimizations, while NIBRS data can. For instance, using NIBRS data, agencies can examine how the vulnerability for sexual violence varies by age. Among children and adolescents who experienced violence, more than half (52.4 percent) of those victimizations involved a rape or violent sexual assault. By comparison, about 1 in 10 (9.4 percent) adult victims of violence experienced a rape or sexual assault.

NIBRS data also show that, regardless of age, females are over nine times more likely than males to be victims of sexual violence reported to law enforcement. This means that regardless of age, a rape or sexual assault victimization is more likely to involve a female victim.⁴ It might not be a surprise to most readers that females are more likely to experience sexual violence than males, but it may be less obvious to most that victims of sexual violence tend to be very young children and young adolescents. Figure 2 shows that, in 2015, the rate of female sexual violence victimization peaked at ages 4 and 15, and then declined steadily after age 15. Though males have a lower overall risk of experiencing sexual violence, they account for one in four victims of sexual violence under the age of 14 and are most at risk for sexual assault victimization at age 5.

Characteristics of Sexual Violence Victimizations

NIBRS data provide context about sexual violence victimizations that law enforcement can use to describe the risks to the public. For instance, the data show that sexual assault against juvenile victims is more likely to occur during the daytime, with more than two-thirds of juvenile sexual assaults taking place between the hours of 8:00 a.m. and 8:00 p.m. Sexual violence against adult victims, on the other hand, was not concentrated during the day; NIBRS data show that nearly a quarter of adult victimizations occurred between the hours of 12 midnight and 4:00 a.m.

Media portrayals tend to highlight sexual violence by strangers, but the data show that victimizations are most likely to be committed by someone known to the victim (Figure 3). Across all sexual violence victimizations reported to NIBRS in 2015 in the selected states, fewer than 1 in 10 (7.5 percent) were committed by strangers. The percentage of sexual violence victimizations committed by a stranger was five times higher (15 percent) for adult victims than for juvenile victims under age 18 (3 percent). Nine out of ten juvenile sexual violence victims were sexually assaulted by a friend or acquaintance (49 percent) or a non-intimate family member (43 percent), not a stranger. Among adult victims, the most common perpetrators were friends or acquaintances (61 percent) or an intimate partner (16 percent).

According to the NIBRS data, sexual violence committed by someone known to the victim tends to happen later in the day and to take place behind closed doors. For example, the most common time of day that non-strangers committed sexual violence was 12 midnight, compared to 9 p.m. for incidents perpetrated by strangers. Moreover, when non-strangers committed sexual assault, the most common location was at a home or residence; the most common location for sexual assaults committed by strangers was on a street or sidewalk.

Conclusion

NIBRS data on crimes known to law enforcement can highlight several important characteristics of rape and sexual assault that cannot be known through other data sources. NIBRS data describe the nuances in the characteristics and scope of rape and sexual assault and can also dispel some myths about the nature of sexual violence. The NIBRS data presented here highlight some valuable takeaways for law enforcement agencies that respond to reports of sexual assault to consider:

• While rapes and sexual assaults constitute less than 20 percent of all violent crimes reported to law enforcement, they make up the majority of the violent victimizations experienced by children; a higher potential for sexual violence among young victims of violence suggests agencies consider customized victim services, investigation, and case processing strategies for this population.
• Females compose the largest proportion of sexual violence victims and are at a higher risk of sexual violence overall than males. However, males are at a higher risk of sexual violence when they are children than when they are adults.
• Sexual violence is most often perpetrated by someone known to the victim, especially when the victim is a young child under age 13. Family members commit the majority of sexual assaults of children under the age of five. ♦

Notes:

¹All of the law enforcement agencies in these 15 states are certified to report their crime data to NIBRS and submitted a full year of data in 2015: Arkansas, Delaware, Iowa, Idaho, Kentucky, Michigan, Montana, North Dakota, New Hampshire, Rhode Island, South Carolina, South Dakota, Tennessee, Virginia, and West Virginia.
²NIBRS data downloads through the FBI’s Crime Data Explorer.
³Based on data from 2013 to 2016 reported in table 1 of the FBI’s 2016 Crime in the United States. These figures incorporate the revised rape definition implemented by the FBI in 2013; see FBI, “Rape,” 2016 Crime in the United States.
⁴In general, 85 percent of sexual violence reported to the police involves a female victim (according to 2015 NIBRS data).