He’s trying to set up a natural experiment by comparing the revenues generated by his upcoming collection of short stories against those genrated by his last. I’m not entirely convinced that the earlier book provides the best control conditions, but I still think it will be interesting to see how this turns out. He will make the book available in a number of versions at different price points:

• E-book: Free
• Audio: Free (but donations accepted for both of these versions, if you feel like making one)
• Print-on-Demand Trade Paperback: $16, probably. This includes the physical book, with one of four covers done by well-known artists
• Premium Hardcover: $250, only 250 available. High class printing, embossed cover, a sd disk with the ebook included, and custom endpapers which consists of original notes and documents provided by his (often famous) friends
• Commission a new story: $10,000, one only. Sold months before the project was announced, so almost certainly underpriced

He’s also going to experiment with selling some ads to go in the free versions, and a few other things. The main problem with this experiment is that the people that demand proof that free works aren’t actually interested in proof, or data. If they were, they would doing their own business model innovation instead of trying to pretend that the new ideas are evil and must be shunned.