I wish this article was out when I was still a course assistant in the biostats department—a lot of students could have used the info here. Aside: As somebody who has herniated a disc and seriously injured a shoulder, I’m still appalled by how often I’m told (by well-meaning physicians) to get an MRI. Nothing in the literature supports the notion that MRIs are useful or definitive for either injury. (Via Tyler Cowen.)