Meta-analyses and other methodological issues in meditation research: Reply to Orme-Johnson and Dillbeck (2014)

We are grateful to Orme-Johnson and Dillbeck (2014) for raising several potential methodological concerns they have with our meta-analysis of the psychological effects of meditation and for thereby providing us with the opportunity to clarify these points. Orme-Johnson and Dillbeck raised 4 points that they believed might have led to unfair treatment of studies that reported the effects of transcendental meditation (TM). First, they were concerned with the way we aggregated effects over different categories of variables. Second, they disagreed with our contention that there might have been some upward bias in the effects reported for TM studies. Third, they argued that the results from TM studies do not differ depending on whether studies were done by researchers affiliated with TM institutions, and 4th, they questioned the completeness of our selection of TM studies. We still believe that our methodology for reporting study results was justified on theoretical grounds and argue that the results for all variable categories are readily available in our analysis. We also still find some indication of upward bias for TM studies, even using the method they propose. We cannot say much regarding author affiliation because we did not raise that point, and, last, we have to concede that we indeed missed some TM studies. Yet this omission did not have any substantial practical consequences concerning our conclusions. We end with a short discussion about how meditation research should be conducted in the future.