Calculating an effect size from Cognition Education on Vimeo.

https://ollieorange2.wordpress.com/2014/09/24/half-of-the-statistics-in-visible-learning-are-wrong-part-2/

Who is correct?

Is the educational community really not checking researchers?

Would the educational community really put someone in charge of the Australian Institute of Teaching and School Leadership who has made strong recommendations that now seem to be questioned?

We are being told that we need to use researched based practices. Which research can we trust?