Expert Commentary

Estimating the incidence of rape and sexual assault: The problem of under-reporting

2013 report from the Bureau of Justice Statistics and the National Research Council on ways to improve the accuracy of surveys on the incidence of rape and sexual assault.

Every April in the United States, Sexual Assault Awareness Month is observed with educational campaigns coordinated by the National Sexual Violence Resource Center. According to a 2013 report from the Bureau of Justice Statistics (BJS), rates of sexual violence have declined in recent decades, but it remains an immense problem: An estimated 22 million women in the United States and roughly 1.6 million men have been raped in their lifetimes. Beyond immediate costs such as medical expenses and missed wages, as well as the potential of life-changing infections and unwanted pregnancies, sexual assault can have devastating long-term impacts, including post-traumatic stress disorder, depression and more.

According to the 2013 BJS report, in 2010 just 35% of sex assaults were reported to the police. Such under-reporting can lead to incidence estimates that are significantly lower that actual rates. The annual National Crime Victimization Survey (NCVS), compiled by the Bureau of Justice Statistics (BJS), is no exception: Other surveys have produced higher incidence estimates, prompting concern that the design of the NCVS might be leading to particularly pronounced under-reporting.

To address this issue, the BJS launched a multi-year investigation with assistance from the U.S. National Research Council. They convened a panel of experts — including those offering both criminal justice and public health perspectives — to provide recommendations on how to more accurately measure rape and sexual assault on the NCVS and other household surveys. The panel examined issues such as the “legal definitions in use by the states for these crimes, best methods for representing the definitions in survey instruments so that their meaning is clear to respondents, and best methods for obtaining as complete reporting as possible of these crimes in surveys, including methods whereby respondents may report anonymously.”

Final recommendations from the panel are contained in a 2014 report, “Estimating the Incidence of Rape and Sexual Assault.” Its key findings include:

  • The NCVS is “efficient in measuring the many types of criminal victimizations across the United States, but it does not measure the low incidence events of rape and sexual assault with the precision needed for policy and research purposes.” Instead, the Bureau of Justice Statistics should develop an independent survey — separate from the National Crime Victimization Survey — for measuring rape and sexual assault.
  • “The context in which survey questions are asked is a critical element in obtaining accurate responses in any survey; it is particularly critical for questions about incidents of rape and sexual assault. The panel believes that framing these questions within a criminal context limits accurate responses.” Therefore, the “questionnaire and protocols for the recommended new survey should have a neutral context, such as a health survey.”
  • “The current data collection mode and methods … do not provide adequate privacy for collecting information on rape and sexual assault. This lack of privacy may be a major reason for underreporting of such incidents.” For example, the use of “audio computer-assisted self-administered interviewing technology,” as well as only interviewing one household member, are steps that would increase respondent privacy.
  • More specific survey questions could be understood more consistently and lead to more accurate reporting rates: “Words such as ‘rape’ and ‘sexual assault’ … may not be consistently understood by survey respondents. Other surveys have used more behaviorally specific words to describe a specific set of actions.”

The report emphasizes that increased accuracy in reporting holds broad policy implications: “Understanding the frequency and context under which rape and sexual assault are committed is vital in directing law enforcement and victim- support resources. These data can influence public policy in the areas of public health, mental health, and education. They also can be used to identify and implement interventions that will reduce the risk of future victimizations.”

Related reading: For further information on sexual violence in the United States, see the March 2013 report “Female Victims of Sexual Violence, 1994-2010”; for additional reading on sexual violence around the world, see the 2010 World Health Organization report “Preventing Intimate Partner and Sexual Violence Against Women” as well as a 2013 study from Harvard University, “Explaining Rape during Civil War: Cross-national Evidence, 1980-2009.”

Keywords: crime, sexual assault, sex crimes

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