Yesterday I had to miss the debate on meta-analyses on #rED18 but I did read the post by Robert Coe.
It’s true there has been quite a stir about Hattie and meta-analyses lately, and to me there are different aspects to the discussion.
I did notice that when effect sizes are shown in a different way, people can spot the complexity that’s often being obscured.
Compare the way Hattie notes effect sizes in his infamous lists of effects, e.g.:
And compare that with this graph, taken from Dietrichson et al., 2017.:
In this second example you can see the range of effects that are hidden behind the average effect size. It’s still an abstraction of a more complex reality, but it invites people who are interested to check what makes the difference between effect sizes noted for small-group instruction so big, or it shows that while coaching and…
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