"Do bad things happen when works fall into the public domain?" A sequel

Readers of this weblog may remember "Do bad things happen when works fall into the public domain?", the 1709 Blog seminar held just over a year ago in which Professor Paul J. Heald gave a spell-binding account of the gap between myth and reality when books drop out of copyright protection and become free to all to exploit.

Well, prompted by some questions and constructive comments from an unusually well-informed audience, Paul has built upon his earlier work, as you can see from the chart above, which is explained in The Atlantic and Slate.  He explains:

"Preliminary data from a random sample of new books available from Amazon (each from a unique ISBN) shows that works in the public domain are more widely available than works protected by copyright. Copyright owners seems substantially less willing to make their titles available to the public. The data needs to be adujsted to account for the number of books published per year, but I suspect that adjustment will likely exaggerate the positive public domain effect."

Paul reminds us that the chart does not measure sales -- just the availability of titles.