Double jeopardy - Double remedy? The effectiveness of self-affirmation for improving doubly disadvantaged students' mathematical performance.

This study examines the effectiveness of a self-affirmation intervention to improve academic achievement for students with a "double-jeopardy status" of belonging to two potentially disadvantaged groups at the same time: girls with a minority background. The method established in the U.S. is adapted to the German cultural context and evaluated for its immediate and medium-term efficacy on math achievement among girls as well as among ethnic minority youth after the transition to secondary school. We applied a double-blind pre-post experimental design with randomized treatment allocation in 11 schools (N = 820, seventh graders with various ethnic backgrounds). Following the intervention of a brief in-class writing assignment about their personal values, students performed a standardized mathematics test. A follow-up achievement test, but no intervention, was administered eight weeks later to assess the midterm effectiveness of the treatment. Between assessments students received a written feedback about their scores in the math test. The multi-level linear model results show that (1) double-jeopardy in math performance exists, as shown by independent negative effects of female gender and Turkish or Arab minority group membership; (2) Girls from all ethnic backgrounds and students with Turkish immigrant background in the intervention group performed significantly better in the mathematics test immediately after the intervention than their peers in the control group. (3) Eight weeks later, the intervention effect only persisted for students with minority ethnic backgrounds: Turkish and Arabic students in the intervention group scored significantly higher in the standardized mathematics test compared to their peers in the control group. (4) We found no support for a triple interaction effect of treatment, ethnic background, and gender. That is, girls with a Turkish or an Arabic background did not benefit more from the self-affirmation intervention than other minority or female students. Results are discussed in relation to self-affirmation theory and how such interventions can be applied in secondary school mathematics curricula.