Psychometric Properties of the Sexual Services Acts Materials for Pay (SSAMP) Index: Identifying the Virtual, In-Person, and Material Sex Trades for Financial Compensation.

Exchanging sex for financial compensation is thought to be underreported primarily because extant studies (1) use a single item to capture a complex, stigmatized phenomenon, and (2) do not capture the complex types or reasons why people engage in the sex trades. Few survey studies have explored the sex trades among university students. This study evaluated the psychometric properties of a newly developed measure, the Sexual Services Acts and Materials for Pay (SSAMP), among university students. Surveys were administered to undergraduate ( = 544, time 1;  = 362, time 2) and graduate ( = 331, time 1;  = 187, time 2) students two weeks apart at a predominantly White, public, Midwestern university. Findings suggested that our index had (1) strong convergent validity with the single item used in prior studies, (2) identified more cases of sex trading than the single item, (3) good internal consistency reliability (4) moderate to strong test-retest reliability, and (5) strong discriminant validity. Exploratory factor analysis revealed that items loaded above .59 on a single factor. To our knowledge, this study is the first to evaluate a multi-item sex trades measure in the U.S. Future research should continue to advance the SSAMP and adapt this index to provide credible estimates and nuanced understanding of the sex trades across contexts.