2019 Volume 15 Issue 1 Pages 121-134
In this paper, we apply ‘Equating’ by Item Response Theory (IRT) to some mathematics achievement surveys carried out by A City educational administration. Besides, to analyze with Latent Class Growth Analysis (LCGA), we investigate the trends of achievement gap from fourth to ninth grade. Findings are as follows. First, as a result of the analysis with LCGA, the changes of academic ability from fourth to ninth grade are divided into four groups. The differences in educational achievement among these four groups have already appeared at the time of fourth grade, and the trajectory of one group does not intersect with that of another group. Second, the characteristics of children differ among the four groups. The lower the academic ability is, the higher the proportion of those receiving schooling aid is. Also, our analysis suggests that boys' academic ability tend to be polarized. Without IRT, we cannot found growing achievement gaps, it is possible that analysis without IRT underestimates inequality.
