Rebuttal of Atkins et al. (2017) critique of the Öst (2014) meta-analysis of ACT

Atkins et al. strongly criticize my (Öst, 2014) systematic review and meta-analysis of ACT. The bulk of their re-examination of my article is divided into four parts: a) Selection of studies, b) Ratings of methodological quality, c) Meta-analysis, and d) Judgments of quality of evidence. It is evident from my paper that I have refuted their claims regarding each of these parts. Regarding a) Selection of studies I showed that only four studies had a cell size of less than 10 and their inclusion did not change the mean effect size or increased variability. Concerning b) Ratings of methodological quality I have showed that my ratings were reliable and had accuracy. As for c) Meta-analysis, I have demonstrated that I got very similar results to those of A-Tjak et al. (2015) that Atkins et al. describes as a much better meta-analysis. Regarding d) Judgments of quality of evidence, Atkins et al. brought up 23 studies for which they argued that I have done an incorrect evaluation but for every single study I have disproved their arguments and maintain my 2014 evaluation of the evidence base of ACT. Thus, there is no reason to follow Atkins et al. suggestion that my review “should now be set aside in making decisions regarding the treatment efficacy of ACT.”