The main conclusion of Mathematica's hefty study of teacher certification routes isn't much of a surprise to anyone who has had to pay attention to the decades long debate on "alternatively certified" teachers. Teachers with up to several years of experience who entered the classroom using an alt cert route are as good at raising elementary students' reading and math scores as counterpart teachers who completed a traditional university program. Yada, yada, yada.
But there's one great finding worth highlighting. Too much coursework taken while teaching appears to actually hurt the ability of teachers to be effective--something we've been contending with no real evidence for years. Students whose teachers were in the subset of alternatively certified teachers still taking courses toward certification or a degree scored lower in reading and math than did students of their traditionally certified counterparts.
In designing their alternative routes, many states have willingly ignored the grueling pressures faced by first-year teachers, while exhibiting quite a bit of sensitivity to ed schools' desire to fill their rolls. Perhaps here's some news that will get some attention: It's the students who pay.
Those results dovetail with NCTQ's contention (see here, for example) that most alternative cert programs too closely resemble the standard ones, requiring too many pedagogy courses and setting all too low admission standards.