>> To identify factual inaccuracies, Warne’s team used as a benchmark a consensus statement on intelligence research published in 1997 by Linda Gottfredson et al

Is the best way to define 'fact' really a twenty year old study?

Also, even if the results are believed, it doesn't seem to be a big deal. Afterall, they're reporting an average of 1 factual inaccuracy per book. When each book presents hundreds or thousands of truth claims, is 1 factual inaccuracy per book noteworthy? I'm willing to bet a much larger percentage of the 'scientific consensus' they define as 'fact' is in fact wrong.