Trend Plots of Average Mathematics Achievement for Girls and Boys
For the TIMSS 2023 countries with comparable data from previous TIMSS assessments, Exhibit 1.2.11 contains graphs of average mathematics achievement across assessments for girls and boys. In each country graph, the y-axis ranges 120 points with a scale interval of 10 points, but a different part of the scale is shown according to each country’s average achievement. Generally, the difference in average mathematics achievement between girls and boys has remained relatively stable across TIMSS assessments. However, the achievement gap favoring boys widened in some countries in TIMSS 2023. Notably, several countries with no difference between girls and boys in TIMSS 2019 had a gap favoring boys in TIMSS 2023, this change in flagging differences as statistically significant was observed in 14 countries. In three countries the achievement gap was closed such that the difference between girls and boys was flagged as statistically significant in 2019, but not in 2023.
Exhibit 1.1.9 displays changes in achievement across assessment years for the countries and benchmarking participants that have comparable data from previous TIMSS assessments. In each country graph, the y-axis ranges 120 points with a scale interval of 10 points, but a different part of the scale is shown according to each country’s range of average achievement. 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.
Across the (up to) 7 time points 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 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. 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.
Read More
Exhibit 1.2.11: Trend Plots of Average Mathematics Achievement for Girls and Boys
Mathematics Grade 8
◊ There was no TIMSS fourth grade assessment in 1999. See Appendix A for country participation in previous TIMSS assessments.
The scale interval is 10 points for each country, but a different part of the scale is shown according to each country’s average achievement.
Students’ gender information was obtained from school tracking data.
