Dan Goldhaber's and Stephanie Liddle's Center for Education Data & Research newly-posted working paper assessing the value-added of teacher prep programs will have a full discussion in the October issue of the Teacher Quality Bulletin, but because it is one of very few studies of its kind, it also deserves immediate mention.

Cobbling together information on teachers and students from six different databases, the authors found that while only a small portion of the overall variation in the effectiveness of teachers is explained by where they were prepared, the "differential in the average effectiveness of the teachers credentialed by various programs is meaningful, in fact at least as important as years of experience and degree level." 

As to why differences in effectiveness occur, particularly as regards the relative contribution of admissions standards versus training as well as the impact of program features — well, there the authors don't have the data yet to support even speculation.         

From the process of obtaining data to final conclusion, the study shows both the difficulties and limitations of value-added research, while pointing to its great promise.  More on that in a later discussion.

Julie Greenberg