LAUSR

Abstract. Rumination is central to understanding the onset and maintenance of non-suicidal self-injury. Yet, no study has evaluated whether reported differences in rumination between people with and without a history of self-injury represent genuine group differences. The present study reports an investigation into the measurement invariance of three common measures of rumination in university students with and without a history of self-injury (total N = 1,519). Results revealed configural invariance for the Ruminative Responses Scale (RRS), the Ruminative Thought Style Questionnaire (RTSQ), and the Repetitive Thinking Questionnaire (RTQ). Additionally, the RTSQ and RTQ supported metric invariance, while the RRS supported partial metric invariance. Further, the RTQ demonstrated partial scalar invariance while the RTSQ demonstrated full scalar invariance. The current findings suggest that observed differences using the RTSQ and RTQ reflect genuine differences in rumination between people with and without a history of self-injury, while researchers using the RRS are advised to account for differential item functioning.