An interesting 2006 survey of MD, PhD, PsyD and MSW programs and the therapy training offered/required:
http://rr4cc.org/pdf/National_Survey_Psychotherapy.pdf
This really doesn't show how effective each group is at providing therapy (nor how effectively taught they are in each modality), but it shows that:
1. 93% of MD programs require CBT supervision compared to 53% of PhD, 20% of PsyD and 21% of MSW programs
2. 96% of MD programs require psychoanalytic/pyschodynamic supervision compared to 10% of PhD (only 57% offered), 8% of PsyD, and 15% of MSW programs.
3. 72% of MD programs offered DBT supervision, compared to 69% of PhD, 56% of PsyD, and 46% of MSW programs.
4. "The 2 disciplines with the largest
number of students and emphasis on clinical training
professional clinical psychology (PsyD) and social
workhad the largest percentage of programs (67.3%
and 61.7%, respectively) not requiring a didactic and
clinical supervision in any EBT."
And many more interesting tidbits.