The 2006 Cochrane Collaboration review was based on just eight studies, and ended with a call for more research to assess the program’s efficacy. In the interve

The 2006 Cochrane Collaboration review was based on just eight studies, and ended with a call for more research to assess the program’s efficacy. In the intervening years, researchers answered the call. The newer review also applied standards that weeded out some weaker studies that drove earlier findings. In the last decade or so, researchers have published a number of very high-quality randomized trials and quasi-experiments. Of the 27 studies in the new review, 21 have randomized designs. Together, these flip the conclusion. (from that NYT link)