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JAMA Pediatrics Journal Club Slides:Trajectory Analysis of the

Campus Serial Rapist Assumption

Swartout KM, Koss MP, White JW, Thompson MP, Abbey A, Bellis AL. Trajectory analysis of the campus serial rapist assumption. JAMA Pediatr. Published online July 13, 2015. doi:10.1001/jamapediatrics.2015.0707.

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• Rape on college campuses is detrimental to young women’s well-being, reduces equal access to education, and creates an unwelcoming campus climate.

• This long-standing problem has recently been addressed by a presidential proclamation, federal legislation, advocacy groups, and popular media.

• Many of the resulting initiatives assume that most college men who perpetrate rape are serial rapists.

• The scientific foundation for this perspective is surprisingly limited.

• Study Objective

– To determine whether a group of serial rapists exists by identifying cohesive groups of young men, indicated by their trajectories of rape likelihood across high school and college.

Introduction

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• Latent class growth analysis of the 2 largest longitudinal data sets of adolescent sexual violence on college campuses.– The derivation data set was collected from August 1990 through April

1995 (4 assessments used).– The validation data set was collected from March 2008 through May

2011 (5 assessments used).

• Data were collected via longitudinal self-report survey at 2 different university campuses in the southeastern United States.

• Participants were male college students from the 2 universities.– Derivation data set: n = 850.– Validation data set: n = 795.

Methods

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Methods

• Outcomes– Rape perpetration—consistent with the Federal Bureau of Investigation

(FBI) definition—was assessed using the Sexual Experiences Survey.

• Design Limitations– A limitation of this design, and others that assess rape perpetration, is an

inability to state whether multiple rape acts reported at a single assessment were perpetrated in the same or different assaults.

– Both data sets were collected in the southeastern United States, which strengthens comparability but possibly limits generalizability.

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Results

• With the 2 data sets combined (N = 1645), 177 men (10.8%) reported behavior that meets the Federal Bureau of Investigation definition of completed rape.

• 84 of the 177 men (5.1%) committed rape before college.– Of these 84 men, 50 (59.5%) did not perpetrate during college.

• 127 of the 177 men (7.7%) committed rape during college.– Of these 127 men, 92 (72.4%) did not perpetrate before college.

• Most men (68 [74.7%]) who committed college rape only did so during 1 academic year.

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Results

• A 3-trajectory model statistically fit the derivation data set better than competing models, and this fit was replicated in the validation data set.

• Trajectory patterns were consistent across data sets and interpreted as follows:

– Low or time-limited (91.7%): Men in this group had a consistently low likelihood of committing rape across time; although 47 men in this group committed rape, none did so at more than 1 assessment.

– Decreasing (5.6%): Men in this group had a high likelihood of perpetrating rape before college, but this likelihood drastically decreased shortly after matriculation.

– Increasing (2.7%): Men in this group had a low likelihood of perpetrating rape before college, but this likelihood drastically increased shortly after matriculation.

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Results

Estimated Probabilities of Committing Rape for Each Trajectory Group Across Time

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Comment

• Neither data set supported a cohesive group of men who consistently committed rape across emerging adulthood.

• The men most likely to commit rape before college were not the men most likely to do so during college.

– Those who arrived on campus seemingly at greatest risk to commit rape decreased their perpetration likelihood across the early college years.

– A small group of men who were unlikely to perpetrate before college drastically increased their perpetration likelihood after matriculation.

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Comment

• Results from these 2 studies suggest there are approximately twice as many men on college campuses who have committed rape than previously reported.

• Most college men who perpetrated rape did so during a relatively limited time.

• Exclusive emphasis on serial predation to guide risk identification, judicial response, and rape-prevention programs is misguided—4 in 5 men who have committed campus rape will be missed.

• Outcomes of this study reinforce the need to do the following:

1. Avoid a “one-size-fits-all” approach to campus rape prevention.

2. Promote sexual and relationship health before high school.

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Contact Information• If you have questions, please contact the corresponding author:

– Kevin M. Swartout, PhD, Department of Psychology, Georgia State University, 140 Decatur St, Ste 1108, Atlanta, GA 30303 (kswartout@gsu.edu).

Funding/Support• Data collection was supported by grants R03HD053444 and

R15HD065568 from the Eunice Kennedy Shriver National Institute of Child Health and Human Development at the National Institutes of Health (Dr Thompson), grant R01MH45083 from the National Institute of Mental Health (Dr White), and grant 98WTVX0010 from the National Institute of Justice (Dr White).

Conflict of Interest Disclosures• None reported.