This is a guest post by Dorothy Grant, Peter’s wife.

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Sarah just informed me that the Giant Obvious Change to Amazon’s algorithms wasn’t so obvious – not to authors who are busy writing and moving. So, let’s talk about organizing book promotions in the current market.

About the time Amazon shook up the writing world by releasing a competitor to Scribd and Oyster (namely Kindle Unlimited, or KU), it also implemented a major revision to its sales ranking algorithm. The obvious impact was that KU borrows have the same impact on sales rank as an immediate sale, but no payment is made until 10% of the text is read. This had the effect of decoupling the strict cause and effect relationship between a book’s actual sales and its sales rank.

However, Amazon also implemented a more subtle but much more massive change to the algorithm. The name of…