Before revision: Hattie himself admitted that half of the statistics in Visible Learning were calculated incorrectly throughout the book.John Hattie admits that half of the Statistics in Visible Learning are wrongTopphol, Arne Kåre.
After revision: Hattie himself admitted that his calculation of the Common Language Effect Size (CLE), which was meant to facilitate interpretation of the more common effect size d in Visible Learning , was done incorrectly throughout the book.John Hattie admits that calculation of the CLE statistic in Visible Learning was wrongTopphol, Arne Kåre.