Methodology: Constructing a socioeconomic index for timss trend analyses

Abstract

To assess education system trends in the inequality of educational outcomes, a robust socioeconomic index for TIMSS trend analysis is needed. This chapter begins by outlining the TIMSS data and sample design, as well as changes in the sample design over time, with special emphasis on the aspects that are specifically related to family socioeconomic status and student achievement. To analyze trends over the entire 20 years of TIMSS data, the analysis was limited to education systems that participated in the first cycle in 1995, the most recent cycle in 2015, and at least one other administration in between. After assessing the completeness of the data, 13 educational systems were included in the study: Australia, Hong Kong, Hungary, Islamic Republic of Iran, Lithuania, New Zealand, Norway, Republic of Korea, Russian Federation, Singapore, Slovenia, Sweden, and the United States. Items used for constructing the SES index were the number of books at home, home possessions, and the highest level of education of either parent. Students in each educational system were grouped into high- and low-SES groups based on the SES distribution for a given year. Constructing a consistent measure of SES across all TIMSS cycles is an important contribution to research that uses TIMSS for trend analyses. In addition to analyzing the achievement gaps over time, examining trends in performance among low-SES students in each education system provides additional information on how education systems are addressing the issues facing disadvantaged students.