John Hattie #

02.12.2012 10:37

1

Thanks for contacting me.

I have found the method I used and indeed Topphol is correct. As he noted in his article: “My conclusion so far is that the CLE-values Hattie offers must be wrongly calculated.” It is. To calculate CLE from d requires finding the integral of the normal distribution from-infinity to d/sqrt(2), and my programming let me down! Thanks for Arne Kåre Topphol for noting this error and it will be corrected in any update of Visible Learning. The error does not affect any of the effect-sizes, or change the story in the book. Readers can have confidence in these matters, but the use of the CLE should be discarded. I have since calculated the correct values of the CLE and these are available from me upon request. I am grateful to Topphol for noting this error, and for your team in contacting me so I could clarify.

John

So does this settle the matter?

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