Electioneering as Profiteering
You've done it again. I love you when you send me Kashi crackers and Amy's canned soups. I love you when you sell me mp3s and Kindle books. I love the way AWS cradles my Dropbox. This Glacier thing sounds cool. And for all that is holy Amazon Prime is the best thing ever. But today I'm breaking up with you for 10 minutes.
Just because someone that you employ can make a red and blue heat map of the United States based on book purchases from your website doesn't mean you should let them. That's not some big data you're crunching, that's bad data analysis.
The magic in public opinion polling is the random sample. Unless you're YouGov/Polimetrix in which case the magic is Doug Rivers. The people who've purchased books over the past 30 days aren't even a random sample of your own customers let alone the country's eligible voters.
Your Election Heat Map does in fact “provide one way to follow the changing political conversation across the country during this election season,” but with a junk chart that re-inforces overly simplistic notions of political polarization based on your own encoding choices and measures nothing of substance what so ever. And thanks for updating this map every day.
You can do better.
UPDATE If you're looking for a book about polarization instead of adding to the din about polarization, let me suggest purchasing Morris Fiorina's Culture War? The Myth of a Polarized America from Amazon (of course).