Sexual violence is a major problem in America, and the federal government has various programs to combat it. But those efforts might be more effective if Uncle Sam had a better idea of what he’s fighting.

The problem: Federal sexual violence statistics are confusing. “Rape is rape” makes a good protest sign, but it doesn’t begin to explain the ways the federal government classifies these violent acts.

Four agencies manage 10 data collections that use 23 different terms to describe sexual violence, according to a Government Accountability Office report, which said the collections “rarely use the same terminology to describe sexual violence.”

“For example,” GAO said, “the same act of sexual violence could be categorized by one data collection effort as ‘rape,’ whereas it could be categorized by other efforts as ‘assault-sexual’ or ‘nonconsensual sexual acts,’ among other terms.”

These differences can result in widely differing estimates for similar-sounding offenses.

Consider how three data sets counted rape cases in 2011.

The National Intimate Partner and Sexual Violence Survey (NISVS) by the Centers for Disease Control and Prevention said there were 1.9 million rape victims. The National Crime Victimization Survey (NCVS), administered by the Bureau of Justice Statistics, counted 244,190 “rape/sexual assault victimizations.” The FBI’s Uniform Crime Reporting Summary Reporting System (UCR-SRS) said there were 84,175 “forcible rape/rape offenses reported.”

Sen. Claire McCaskill (D-Mo.) requested the GAO report and urged agencies to develop standards for sexual violence data.

“As we continue to make progress in combating sexual assault and empowering survivors to come out of the shadows, we’ve got to have a way to measure that progress that’s standard and transparent,” she said. “Without the ability to make apples-to-apples comparisons across populations — whether that’s college students, our military or other groups — it’s difficult to measure trends over time and determine how we’re doing in terms of reducing incidents and boosting reporting.”

The difference in sexual violence statistics from official sources can hinder attempts to prevent and fight criminal activity that is already underrated, particularly by men. “It detracts from the point that all of the studies say this is a serious problem that needs to be addressed,” said Kristen Houser of the National Sexual Violence Resource Center.

No matter which data set is used, the numbers might be low.

“Victims often do not report sexual violence to law enforcement officials due to feelings of guilt, shame, and embarrassment; fear of the perpetrator; or fear of not being believed, among other reasons,” GAO said. “Therefore, the occurrence of sexual violence is considered to be underestimated.”

Confusion over terms doesn’t help.

Most people would say sexual violence with vaginal penetration is rape, and six data collection efforts agree with that. Two programs, however, call it “nonconsensual sexual acts” or “staff sexual misconduct,” according to GAO, two say it is “sexual assault” or “assault-sexual,” one says it is “sexual coercion” and another uses the term “penetrative sexual assault.”

There are also differences within agencies and their data collections.

CDC’s National Intimate Partner and Sexual Violence Survey “characterizes vaginal penetration of a victim as ‘rape’ if the act involves the use of physical force or threats to physically harm the victim,” GAO reported. Yet the survey calls the same act “sexual coercion” if “the victim is verbally pressured in a nonphysical way, for example if the perpetrator uses their influence or authority.”

GAO urged the Office of Management and Budget (OMB) to “establish a federal interagency forum on sexual violence statistics. The forum should consider the broad range of differences across the data collection efforts to assess which differences enhance or hinder the overall understanding of sexual violence in the United States.”

The departments of Education, Justice and Health and Human Services agreed with GAO recommendation to make publicly available more of the information behind their sexual violence statistics. According to GAO, OMB said none of the agencies collecting sexual violence data were “far enough along in its research for OMB to develop guidance or identify best practices at this time.”

Meanwhile, the lack of guidelines means confusion remains.

Yet, the disparity among the data collections doesn’t necessarily hurt efforts to combat sexual violence, said Neena Chaudhry, education director and senior counsel of the National Women’s Law Center.

“Whatever numbers we have,” she said, “we know that sexual assault is a very serious problem across the country.”

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