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Book Amazon sales data for books about TMS

Discussion in 'General Discussion Subforum' started by Forest, Jul 6, 2014.

  1. Forest

    Forest Beloved Grand Eagle

    Hi everyone,

    I've been gathering book sales data for books about TMS recently, and I thought that I would share what I've found.

    Amazon lists roughly 32 million books on its site and it publishes a "Sales Rank" for most of them. I've created a list of books about psychosomatic pain that allows us to compare the Amazon sales ranks of the different books. I wanted to make the most comprehensive and helpful list I could, so I used data from Amazon to include all books about psychosomatic pain (or equivalents) that tend to be bought by people who by other TMS books.

    The largest factor determining Sales Rank is the amount of time since the last sale. Because of this, Amazon sales rank can fluctuate significantly, based on whether the book had a good day or a bad one.

    For each book, the list includes different entries for hardcover, paperback, mass market paperback, and kindle editions, depending on how many editions are available.

    By watching the fluctuations in the official sales rank, the list is able to calculate an estimate of how many books are sold per month. I've been updating the list since late June, so the July sales estimates are probably pretty good. However, since I didn't start until late June, the June sales figures should be ignored as they are incomplete.

    Because Amazon lists approximately 32 million books on its site, any book with a sales rank of over 16 million can be considered "above average." By that measure, TMS books are doing exceptionally well.

    I hope people find the list to be interesting and helpful. If you have any questions, please just let me know!

    Last edited: Jul 6, 2014
    Ellen and Eric "Herbie" Watson like this.
  2. Eric "Herbie" Watson

    Eric "Herbie" Watson Beloved Grand Eagle

    This is awesome forest, thank you so much.
  3. Forest

    Forest Beloved Grand Eagle

    I've received a couple of questions about how the estimates of monthly Amazon.com sales are calculated. Amazon does not release figures on monthly sales for books, so the numbers must be estimated. In the following video I explain my understanding of how this is done:

    The numbers aren't perfect, but I'm glad we have them.
    davidclarke and Ellen like this.
  4. Ellen

    Ellen Beloved Grand Eagle

    A question Forest. Data doesn't include audio books or used books sold through the Amazon site?

    Thanks for the information.
  5. Walt Oleksy (RIP 2021)

    Walt Oleksy (RIP 2021) Beloved Grand Eagle

    Great information, Forest. Glad TMS books are selling well.
  6. davidclarke

    davidclarke Author & Physician

    Having watched the numbers for my book fairly regularly since publication in 2007 I would add that while the sale of one book can jump you from a sales rank of 500,000 to 100,000 fairly easily it takes the sale of more than one book to generate a significant jump in the graph as you get close to the top. Another way to say this is that I believe the curve of sales figures vs sales rank becomes exponential in shape at very high levels.
  7. Forest

    Forest Beloved Grand Eagle

    Unfortunately, the program doesn't allow for tracking anything else but paper and Kindle editions of books. At some point I hope to look for alternatives for audiobooks, and if I find any, I'll add them to my first post.

    I don't know if Amazon factors sales of used books or Amazon Marketplace sales into their Sales Rank. That's a very interesting question, though, and I'd be love to hear if anyone can figure that out.
    I wonder if what you are saying is captured in the idea that book sales follow a power law. I don't want to hijack this thread with a discussion of Power Laws, though, as the subject is very mathematical and therefore not of interest to most people. Therefore, I've started a new thread to reply:

    If you would like to continue this discussion, please reply to that thread rather than this one.

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