Originally Posted by mediax
Whilst this would undoubtedly mean that the category in question did "drive eBook purchasing", I hardly think it's a fair requirement as a "pass mark"!
Good point. I agree completely. My explanation does make it sound like I am using the 50% as a "pass mark".
In fact, I will compare the percentage of that category with the percentages of other categories. The fact that three or four other categories are higher than "just published bestsellers" is the real evidence that this category is not driving eBook purchasing.