BJS Activities on Measuring Rape and Sexual Assault

2011 National:

Purpose
Challenges exist in the collecting of self-report data on rape and sexual assault. For almost two decades, there have been a number of competing national estimates of the level and the change in level of rape and sexual assault. The official estimates of these crimes released by BJS and based on the National Crime Victimization Survey (NCVS) have typically been lower than estimates obtained from surveys contracted for by other federal agencies and by private groups. For example, the National Violence Against Women Survey (NVAWS), sponsored by the National Institute of Justice (NIJ) and the Centers for Disease Control and Prevention (CDC) and conducted in 1995–96, estimated an incidence rate for rape (counting multiple rapes) of 8.7 per 1,000 women aged 18 or older, compared with an incidence rate for rape (including attempted rape) and sexual assault in the previous 12 months of 2.3 per 1,000 women aged 12 or older from the 1996 NCVS.1

Some of the differences in these estimates result from more and less inclusive definitions of rape and sexual assault. The NCVS, for example, emphasizes felony forcible rape, while the National Women’s Study (NWS) employs a much more inclusive definition. Even when the surveys use comparable definitions, however, the methodology used to elicit reports of these events can differ dramatically and produce very different estimates of the incidence of these crimes. A number of discussions have taken place regarding the desirability of various survey design features, including sample design, screening strategy, reference period, bounding, cueing strategy, types of cues, context, and respondent selection. In addition, differing interviewing modes have been discussed, including telephone interviews in NVAWS, in-person interviews as in the NCVS, and more private, Audio Computer Assisted Self-Interview (ACASI) options like those used in the BJS-sponsored National Inmate Surveys of sexual violence among correctional populations.

The differences that arise from using different methodologies and surveying different populations have resulted in debate over the ideal method for collecting self-report data on rape and sexual assault.2

In addition, these differences have resulted in confusion among stakeholders as to which estimates are more accurate. This debate has had the negative consequence of raising doubts about the self-report methodology itself. ..Continued.. by Shannan Catalano, Michele Harmon and Allen Beck, David Cantor