9. Pseudoscience Masquerading as Truth. In some parts of the world, John Hattie's 2008 Visible Learning is a policy bible, since it claims to contain a meta-analysis of the evidence about education which then suggests what actions can be taken to improve both school and system performance in relation to learning outcomes. He looks at "effect size" (for example, to what extent does class size make a difference to learning outcomes?) and reviews all studies related to the effect under scrutiny to calculate an average effect size. The book is full of basic statistical errors (miscalculations and inappropriate baseline comparisons, to name two) and claims that cannot be supported by the evidence - class size having no significant effect being one. A recent review by a leading Canadian statistician concluded that "in summary, it is clear that John Hattie and his team have neither the knowledge nor the competencies required to conduct valid statistical analyses. No one should replicate this methodology because we must never accept pseudoscience." Yet, others have found this book (and several others like it in the past) as like "the Holy Grail of education" . Education seems unusually prone to such works - claims related to the performance of certain methods and policies (e.g. brain-based teaching, whole language instruction for the teaching of reading, the use of school vouchers as a basis for educational choice) that it sometimes looks more like homeopathy than medicine. Diane Ravich captures some of this in her 2014 book The Reign of Error - The Hoax of the Privatization Movement and the Danger to America's Public Schools in which she explores the evidence that the introduction of competition and private sector approaches improves educational outcomes and can find no compelling evidence in support of this proposition having a positive impact on school performance.