I have not had the time to look at the data carefully, but below is a quick tableau (http://www.tableausoftware.com/public/) showing a list of non-fiction ebooks that had appeared on the Amazon Best Sellers list in June. (http://www.amazon.com/Best-Sellers-Kindle-Store-Nonfiction/zgbs/digital-text/157325011/ref=zg_bs_157325011_pg_1?_encoding=UTF8&pg=1)
Assuming Amazon does not change its website’s formatting in the foreseeable future, I should be able to gather some historical data as time goes on and do some fun data and graphical analytics. In particular, I want to see if I can quantify what influences the ranking for books the top 100 list (conditional on the book made it on the list).
For now, the interactive tableau shows all the books from the non-fiction best sellers list for June (except for the 29th, when I computer crashed). If you click on the title of the book, it should update the bottom two charts to show the price and ranking history. The green dots on the top chart are showing the ranking: missing means the book is not on the ranking that day, and darker green means the ranking is higher. Hovering your mouse on the green dot also show you additional data – such as author and url. Finally, by default, the list is sorted by the number of days on the best sellers list, but you can sort it by alphabetical as well. The selector on the right - “freeAlways,” - has a value of 0 if the book is not free on some days. Even from a quick glance, it is clear that the behavior of the free books and non-free books are very different. (Fun fact: there are more books in the free list that starts with a number in the title, like: “50 Super Summer Recipes…” or “63 Super Cleaning Herbs…”.) So if the selector is on the left – so the value ranges from “0 to 0” – then the list excludes all the books that are only on the list when it was free. You can drag the selector to “0 to 1” or “1 to 1” for the other two possibilities.
The default I set for the tableau shows Dale Carnegie’s “How to Win Friends and Influence People,” which changed its price twice over the month of June. From my sample size of one, it appears there’s some correlation between ranking movement and price for non-free books.