The AAP publishes numbers each month which are then revised in the weeks and months after the press release goes out. The figures change because publishers send in updated sales data for a given month for a number of reasons: late returns, unreported sales, sales originally reported in the wrong categories, etc. Today's numbers are going to change over the next few weeks.
You know, if Al Capone had gotten into publishing I don't think the IRS would ever have caught him.
What this means is that all of my analysis is now bunk. The numbers I was using were very likely wrong fairly soon after they were committed to paper. It also means that all the news articles based on the monthly AAP figures - everyone's articles - are all wrong. They were based on fiction. No one really knows what the sales figures are until months and months later.
I'm not sure which bother me more. The fact that i passed along bad data or the fact that everyone has passed along bad data and will continue to pass along bad data.
In the future, when i hear about spectacular sales, I plan to take them with a grain of salt.