The problem with claiming upwards of 95% accuracy when guessing ebook sales based on relative chart positions is that when the people with the real numbers tell us the true figures, and the guestimates turn out to be only 60%-70% accurate, we have a problem. Bookstat, the $10 million paywall book sales calculation site run … Continue reading Data Guy’s Bookstat under-guesses sales on 3 Hachette ebooks by 14,000, throwing Bookstat numbers for non-Hachette titles into doubt