The Programme for International Assessment (PISA) is an important cross-national study of 15-year olds academic achievement. Although it has traditionally been conducted using paper-and-pencil tests, the vast majority of countries will use computer-based assessment from 2015. In this paper, we consider how cross-country comparisons of children's…

Effect sizes have been increasingly emphasized in research as more researchers have recognized that: (1) all parametric analyses (t-tests, analyses of variance, etc.) are correlational; (2) effect sizes have played an important role in meta-analytic work; and (3) statistical significance testing is limited in its capacity to inform scientific…