A conversation with Dr. Ira Casson (who served on the National Football League’s committee on mild traumatic brain injury and co-authored several of its studies on MTBI) reveals that it may be impossible to assess the value of its six-season study. Despite the author’s defense of the methods used to conduct the research, there’s room for skepticism, both in the light of a New York Times story reporting that over 10% of such injuries may have gone unreported and the study’s assumption that all teams reported all injuries.

We asked the League to make the studies’ first author available for this conversation, and they declined.