Sexual Assault Statistics

The following are drawn from the 2010 National Intimate Partner and Sexual Violence Survey (NISVS) conducted by the Centers for Disease Control and Prevention (CDC). These are just a few

Why Are There Different Statistics?

Sexual violence has traditionally been an underreported crime compared to other felonies in its class. As such, different survey instruments attempt in different ways to address the issue of underreporting. Some of the most frequently cited studies on this issue have differing answers on the prevalence of sexual assault—these differences come from differences in methodology.

Primary Difference between Studies:

Several often cited studies on sexual assault, such as the National Intimate Partner Violence and Sexual Violence Survey (NISVS), the National Crime Victimization Survey (NCVS) and the Campus Sexual Assault (CSA) differ in the way they ask about, measure and report rates of sexual assault (such as lifetime prevalence v. annual rate). Differences in methodology or the way statistics are grouped and reported will often produce different results. For example, because the NCVS only asks about crimes, a respondent may not include sexually coercive or forced experiences that they did not consider crimes. A helpful write up of the differences can be found in this Bureau of Justice Statistics report.

The Sexual Victimization of College Women survey points out a discrepancy that different methodological strategies, such as alternative wording and question detail are meant to help capture:

82 women responded affirmatively to questions describing the legal definition of rape that did not include the word rape, i.e. “Since school began in fall 1996, has anyone made you have sexual intercourse by using force or threatening to harm you or someone close to you? Just so there is no mistake, by intercourse I mean putting a penis in your vagina.”

The 82 women who responded yes to a question that met the legal definition of rape were also asked “Do you consider this incident to be a rape.” Of those same 82 women, only 40 (46.5%) considered it rape, 42 (48.8%) did not consider it rape, and 4 (4.7%) answered that they did not know.

Different surveys are designed with different measurement goals in mind, and are meant to answer different questions. It’s important when looking at statistics to look at the way the numbers are reported, and the methodology that led them to those numbers in order to assess what they are really telling you.

For more information:

Bachman, Ronet, and Bruce H. Taylor. "The measurement of family violence and rape by the redesigned National Crime Victimization Survey." Justice Quarterly 11, no. 3 (1994): 499-512.

Koss, Mary P. "The under detection of rape: Methodological choices influence incidence estimates." Journal of social issues 48, no. 1 (1992): 61-75.

Schwartz, Martin D. "Methodological issues in the use of survey data for measuring and characterizing violence against women." Violence Against Women 6, no. 8 (2000): 815-838.

Testa, Maria, Carol VanZile‐Tamsen, Jennifer A. Livingston, and Mary P. Koss. "Assessing women's experiences of sexual aggression using the Sexual Experiences Survey: Evidence for validity and implications for research." Psychology of Women Quarterly 28, no. 3 (2004): 256-265.

Wilson, Laura C., and Katherine E. Miller. "Meta-analysis of the prevalence of unacknowledged rape." Trauma, Violence, & Abuse (2015): 1524838015576391.