Trends in Average Mathematics Achievement
The fourth-grade TIMSS mathematics achievement scale was established in TIMSS 1995, based on the achievement across all participating countries. In 1995, the international mean was set to 500, and the international standard deviation was set to 100, providing the origin of the TIMSS trend scale. Students’ achievement was placed on the same scale with each subsequent TIMSS cycle, most recently for TIMSS 2023. Reporting the achievement data from each TIMSS assessment on the TIMSS trend scale enables monitoring increases or decreases in achievement across assessment cycles.
Exhibit 1.1.9 displays changes in achievement across assessment years for the countries and benchmarking participants that have participated in prior cycles of TIMSS. The trend graphs include a graphical representation of the 95% confidence interval around each cycle mean, depicted as small error bars above and below the average achievement estimate. Confidence intervals of this type have a 95% probability to include the true country average under repeated sampling. Users can select individual countries, groups of countries, or all countries that participated for customized displays of trends.
Across the TIMSS cycles spanning the years from 1995 to 2023, most countries that participated multiple times have had some periods of increases or decreases in average achievement as well as periods of stability. It can be seen that even if estimates of average achievement may be lower or higher for adjacent years, the confidence intervals overlap quite frequently. In cases of larger differences with little or no overlap of confidence intervals, the trends over time indicate more visible changes of larger magnitude.
Exhibit 1.1.10 extends the results of Exhibit 1.1.9, providing more detail about the achievement distributions across assessment cycles and the differences in average achievement between each previous TIMSS cycle and TIMSS 2023. Symbols are used to indicate if an estimate obtained in a prior TIMSS cycle shows a statistically significant difference compared to TIMSS 2023. The direction of the up or down arrow shows whether the previous estimate is higher or lower than the estimate obtained in 2023. For the 49 countries with comparable data in TIMSS 2019, 14 showed an increase in average mathematics achievement in TIMSS 2023, 13 showed a decrease, and 22 had no change. Confidence intervals for the average achievement of each cycle are reported, corresponding to the error bars in the trend graphs in Exhibit 1.1.9. The graphical depiction of the percentiles provides a visualization of the distribution and shows the range of achievement that is observed in each cycle. The overlap of these visual representations of achievement distributions provides a reference for the magnitude of changes observed across TIMSS cycles.
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Exhibit 1.1.9: Trend Plots of Average Mathematics Achievement◊&Exhibit 1.1.10: Trends in Average Mathematics Achievement and Scale Score Distributions
Mathematics Grade 4
Select an exhibit:
Country
Average
Scale Score
95% Confidence
Interval (±2SE)
Difference from
TIMSS 2023
Notes for Exhibit 1.1.9:
◊ There was no TIMSS fourth grade assessment in 1999. See Appendix A for country participation in previous TIMSS assessments.
Ɪ The black bars represent the 95% confidence interval.
Notes for Exhibit 1.1.10:
See Appendix A for country participation in previous TIMSS assessments.
() Standard errors appear in parentheses. Because of rounding some results may appear inconsistent.
See Appendix B.2 for population coverage notes 1, 2, and 3. See Appendix B.5 for sampling guidelines and sampling participation notes †, ‡, and ≡.
Ψ Reservations about reliability because the percentage of students with achievement too low for estimation exceeds 15% but does not exceed 25%.
Ж Average achievement not reliably measured because the percentage of students with achievement too low for estimation exceeds 25%.
Suggested Citation
von Davier, M., Kennedy, A., Reynolds, K., Fishbein, B., Khorramdel, L., Aldrich, C., Bookbinder, A., Bezirhan, U., & Yin, L. (2024). TIMSS 2023 International Results in Mathematics and Science. Boston College, TIMSS & PIRLS International Study Center. https://doi.org/10.6017/lse.tpisc.timss.rs6460