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Interpreting Effect Sizes In Education Research


This article (and the Kraft paper) fails to understand recent work on effect size (e.g. There is no way of interpreting ES as a measure of the effectiveness of the intervention - e.g. the same experiment with the same test using multiple choice answers instead of short form responses will give a very much smaller ES. So we cannot decide policy by comparing ESs [either against each other or against a fixed boundary such as 0.2].

I think a later paper by Simpson gives a gr8 analogy- Simpson, Adrian (2018). Princesses are bigger than elephants: Effect size as a category error in evidence-based education. British Educational Research Journal. Vol 44, Issue 5. Simpson shows comparing sizes of objects on a photograph is akin to comparing effect sizes. He shows if doing this, you could conclude princesses are bigger than elephants. I'm putting together a critique of Hattie's work, who dominate Australian Education & uses this method of comparing effect sizes. Please feel free to contribute here-

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