Classrooms are places of many complexities and while there are common themes sometimes averages may not do it justice. However, the issue is that generalizability of the overall effect is an empirical issue and there are far fewer moderators* than are commonly thought (Hattie, 2009, p 10). It is important to appreciate that the 50,000 studies summarized in the book cover a very wide group of classrooms, with remarkable complexity and the aim of many of the studies was to understand these complexities. * In statistics, moderation occurs when the relationship between two variables depends on a third variable.
Articles in this section
- Why does the Visible Learning research use effect sizes?
- Why do you use an effect size of d=0.40 as a cut-off point and basically ignore effect sizes lower than 0.40?
- What is the preferred timescale over which an effect size can be calculated?
- Is there a bias when using effect sizes in favor of lower achieving students?
- What caution should I take when calculating an effect size?
- Why are effect sizes used when conducting meta-analysis?
- Why can an effect size of 0.40 be gained in a shorter timeframe?
- Can effect sizes be added (or averaged)?
- How accurate are the conclusions drawn from meta-analysis?
- How can the variability associated with each influence be evaluated?