Dr Manocha Discusses the publication bias and its impact upon meditation research literature in this except from his thesis:
“It is widely accepted that positive studies are more likely to be published than negative ones. For example, the Institutional Review Board of the Johns Hopkins University conducted a follow-up of several hundred studies that it had approved to ascertain how many had actually reached publication and found that positive studies were 2.5 times more likely to be published than negative ones and that this phenomenon is associated more with failure of the authors to submit the study than with rejection from journals.
Generally speaking, publication bias is an important factor which needs to be taken into account, since the weight of unpublished, negative studies can significantly change the conclusions of any review that would otherwise report positive findings. In the case of meditation however, I believe that publication bias is probably not yet a significant issue for the purposes of answering fundamental questions about meditation since:
•the majority of studies do not report strongly positive findings in favour of meditation
•in depth quantitative meta-analytical assessment is not yet possible due to the heterogeneity of the studies that have been published.”
More information on Dr Manocha’s thesis can be found here.