Joseph Newhouse and the other RAND researchers have responded to Nyman’s paper arguing that attrition bias biased their results. The RAND researchers were aware of these issues and in fact designed the experiment to avoid incentives for non-random attrition. Most importantly, the basic RAND findings have now been replicated in many other studies (smaller and not always experiments but the results are solid). I call it a knockout for RAND.
It’s a credit to the many insightful commentators on Marginal Revolution that many of these points were made already in the comments on my original post.
Thanks to Jason Furman for the pointer.