Yuliya Kersha — Postgraduate Student, Research Assistant, Pinsky Centre of General and Extracurricular Education; Lecturer, Department of Educational Programs, Institute of Education, National Research University Higher School of Economics.

Address: 20 Myasnitskaya Str., 10100 Moscow, Russian Federation. E-mail: ykersha@hse.ru

It can be inferred from international findings that school socioeconomic composition (SEC) is a major factor of educational inequality in secondary education at the school level. SEC is believed to have a positive relationship with student achievement along with individual student characteristics. However, a review of research methods used in most studies calls the existence of an influence into question.
A study was carried out to evaluate causal relations between school SEC and student achievement. Multilevel regression analysis and propensity score matching (PSM) methods were applied to the panel study Trajectories in Education and Careers data in order to measure the effects of one year of study at schools with low vs. high socioeconomic composition. Correlational and quasi-experimental effect sizes were compared.
Analysis results confirm that school SEC is a key factor of educational inequality in Russian secondary education, the inequality effects of school composition overlapping only partially with those of school location. Within a year of schooling, ninth-graders with similar individual characteristics may lose up to a quarter of standard error in PISA‑2012 scores if attending a school with low socioeconomic composition, while attending a high-SEC school would improve their educational outcomes by the end of the ninth grade. Negative effects were observed for two subject areas, which allows suggesting a systematic impact of SEC on student achievement. The final part of the article describes the theoretical and practical significance of the findings and presents the main directions of further research in this field.