The whole amazon sales rank is so bogus, it is just hype. Lets say one day 20k copies are sold and one format has 75% and the other has 25%. Then the next day 5k copies are sold and the numbers are reversed. Clearly the one that sold a ton more on the 20k day more than made up than the 5k day.
There is no way to tell anything from amazon numbers other than what was popular on a given day. It does not tell you how many titles were sold.
There is no way to tell anything from amazon numbers other than what was popular on a given day. It does not tell you how many titles were sold.