Assessing achievement is a complex task due to its dependence on multiple factors and the hierarchical structure of educational data, yet surveys like TIMSS offer valuable insights into its determining factors like students' mathematics anxiety. However, disregarding the nested structure of data and ignoring the assumptions of models causes poor…

In this multicountry analysis, we generate a student-level measure of socioeconomic status (SES) "mixing" to understand the benefits or pitfalls of placing low-SES children with diverse peers. We conduct this analysis separately for equal and unequal countries that provide the same curriculum to all children regardless of ability level,…