Amazon Election Heat Map 2012

44% Purchased "Blue" Books 

56% Purchased "Red" Books 

  How do we calculate the red and blue percentages on our Heat Map?

Our 2012 Election Heat Map colors each state according to the percentage of red and blue book purchases, based on shipping address, that have been made on Amazon.com during the past 30 days. We take the top-selling political books on Amazon.com and categorize them as "red," "blue," or neutral. We classify books as red or blue if they have a political leaning made evident in book promotion material and/or customer classification, such as tags. We compute percentages, updated daily, for each state and the US by comparing the 250 best-selling blue books during the time period against the 250 best-selling red books during the same time period, including new book launches. If the same book title has multiple formats (paperback, Kindle books and Audible Audio), each format has a separate sales calculation. The list only includes paid, not free Kindle books. All orders during the period are given equal weighting in the calculation. States with higher percentages of red or blue purchases are colored more darkly, and states with an even 50-50 split are colored neutral.   [Amazon]