There are two major types of effect sizes. One is appropriate for research that is experimental in nature such as those based on comparing groups. For example, a class that received a treatment, such as reciprocal teaching, and another class that did not receive the intervention. The other effect size approach is used to establish the impact of an intervention over item (pre-post). They have different interpretations and it is an empirical question as to whether they differ. In Visible Learning (2009) the majority of the effects sizes were based on research that investigated group comparisons. The “MetaX” indicates which of these effect-sizes was used.
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?