Using sophisticated quantitative methods, he is a leading researcher in self-concept and motivation, evaluation of teaching, developmental psychology, sports psychology, peer review and peer support, gender issues, and anti-bullying interventions. JOHN P. JERRIM is a professor in educational and social statistics at the UCL Institute of Education, UK. He received his doctorate in social statistics from the University of Southampton. His research focuses on international comparisons of educational attainment and the evaluation of educational programs and policies. JIESI GUO is a post-doc research fellow at the Institute for Positive Psychology and Education. His areas of interest include educational and developmental psychology with a particular focus on how multiple systems on the cultural, social, and motivational development of youth shape individual and gender difference in achievement choice. THERESA DICKE is a post-doc research fellow at the Institute for Positive Psychology and Education at the Australian Catholic University. Her research interests lie in the realm of organizational, health, and educational psychology. Applying complex quantitative methods, she has extensively studied the role of (occupational) well-being and achievement in school, thus, focusing on students', teachers', and principals' perspectives alike.