What to make of this? John Hattie’s book is one of the most influential books on education to appear in the last few years. For some, it has almost the status of an education bible. If the statement “Half of the statistics in ‘Visible Learning’ are wrong”, can be sustained, what consequences does it have for our teaching practice?
In this and the next post, reblogged from Ollieorange2, the author, a British mathematician and math teachter, finds out exactly what is wrong with Hattie’s statistics.

At the researchED conference in September 2013, Professor Robert Coe, Professor of Education at Durham University, said that John Hattie’s book, ‘Visible Learning’,  is “riddled with errors”. But what are some of those errors?

The biggest mistake Hattie makes is with the CLE statistic that he uses throughout the book. In ‘Visible Learning, Hattie only uses two statistics, the ‘Effect Size’ and the CLE (neither of which Mathematicians use).

The CLE is meant to be a probability, yet Hattie has it at values between -49% and 219%. Now a probability can’t be negative or more than 100% as any Year 7 will tell you.

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Read more in part 1 and part 2 of John Hattie admits that half of the Statistics in Visible Learning are wrong