RT Conference Proceedings T1 To weight or not to weight?: the case of PISA data A1 Jerrim, John A1 López-Agudo, Luis Alejandro A1 Marcenaro-Gutiérrez, Óscar David K1 Evaluación educativa AB International large-scale assessments (ILSA) –like e.g. PISA, TIMSS, PIRLS, etc.– have obtained a high worldwide popularity among researchers to study students’ academic achievement. Nevertheless, in spite of their recently acquired relevance, there are few studies which really account for the complex survey and test designs that they present and follow the technical procedures suggested by their developers. The current study intends to provide researchers with a comprehensive explanation on how these databases should be dealt with and the drawbacks of not employing the recommended procedures. Furthermore, we also alert about the use of methodologies which would not be adequate in the context of these studies, as the common use of student fixed effects. Hence, the main goal of this research is to provide some kind of ‘good practices guide’ which can be a quick reference to researchers. YR 2017 FD 2017-09-25 LK http://hdl.handle.net/10630/14517 UL http://hdl.handle.net/10630/14517 LA eng NO Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. ECO2014-56397-P. DS RIUMA. Repositorio Institucional de la Universidad de Málaga RD 21 ene 2026