Somebody pointed out this research paper to me: https://eric.ed.gov/?id=EJ1231626
Whilst I'm personally pleased that the authors give a positive conclusion, I can't help thinking that their methods and their reporting could have been a lot more rigourous. The paper doesn't seem to pose a clear hypothesis. Their survey questions are not described except very superficially. What is most concerning, is that they don't seem to have used a control group. ... Also they mistyped my name :( ... I wonder if anyone is aware of any other studies on the efficacy of PSPP ? J'