Appendices
Appendix A: Population Coverage and Sample Participation Rates
Appendix B: TIMSS 2023 Longitudinal Curriculum Questionnaire Data
Appendix C: Percentages of Students with Achievement Too Low for Estimation
Appendix D: Organizations and Individuals Responsible for TIMSS 2023 Longitudinal
Appendix A: Population Coverage and Sample Participation Rates
The TIMSS 2023 Longitudinal target population for 2024 included all students enrolled in eligible and participating classes sampled for TIMSS 2023. TIMSS worked with participating countries to ensure efficient sampling design for TIMSS 2023 and sampling implementation for both administration years.
TIMSS 2023 Longitudinal adhered to the same quality standards for sampling implementation as TIMSS 2023, with consideration that some students originally sampled for TIMSS 2023 may not have been assessed in one or both years. In particular, some students assessed in 2023 were no longer accessible in 2024 (i.e., attrition).
The exhibits comprising this appendix provide information about the samples of students assessed for TIMSS 2023 Longitudinal, including population coverage and participation rates for 2023, 2024, and the combined longitudinal samples. More information about the TIMSS 2023 Longitudinal samples can be found in the TIMSS 2023 Longitudinal Technical Report.
Exhibit A.1: Information About the Students Assessed in TIMSS 2023 Longitudinal
Exhibit A.2: Coverage of TIMSS 2023 Longitudinal Target Population
Exhibit A.3: School Sample Sizes
Exhibit A.4: Student Sample Sizes
Exhibit A.5: Participation Rates (Weighted)
Exhibit A.6: TIMSS 2023 Longitudinal Overall Participation Rates (Weighted)
Appendix B: TIMSS 2023 Longitudinal Curriculum Questionnaire Data
National Research Coordinators for participating countries completed a revised version of the TIMSS 2023 Curriculum Questionnaire, which focused on how students are organized for transitioning between grades and the mathematics and science topics taught in Grades 5 and 9. Access the TIMSS 2023 Longitudinal Curriculum Questionnaire data.
Appendix C: Percentages of Students with Achievement Too Low for Estimation
Exhibit C.1: Percentages of Students with Mathematics Achievement Too Low for Estimation (Grades 4 – 5)
Exhibit C.2: Percentages of Students with Science Achievement Too Low for Estimation (Grades 4 – 5)
Exhibit C.3: Percentages of Students with Mathematics Achievement Too Low for Estimation (Grades 8 – 9)
Exhibit C.4: Percentages of Students with Science Achievement Too Low for Estimation (Grades 8 – 9)
Suggested Citation
von Davier, M., Kennedy, A. M., Reynolds, K. A., Gonzalez, E., & Khorramdel, L. (2025). TIMSS 2023 Longitudinal International Results in Mathematics and Science. Boston College, TIMSS & PIRLS International Study Center. https://doi.org
Co-funded by the European Union. Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Education and Culture Executive Agency (EACEA). Neither the European Union nor EACEA can be held responsible for them.