Good catch. Additionally, one of the authors on this is just a student at UWisc, and the other author is also not a professional researcher but instead an author of popular books.
This is not an ad-hominum, but does put into question the statistical training backgrounds of both of these authors to accurate assess the data.
This is not an ad-hominum, but does put into question the statistical training backgrounds of both of these authors to accurate assess the data.