Reexamining psychokinesis: Comment on Bösch, Steinkamp, and Boller (2006)

H. Bo ¨sch, F. Steinkamp, and E. Boller’s (2006) review of the evidence for psychokinesis confirms manyof the authors’ earlier findings. The authors agree with Bo ¨sch et al. that existing studies provide statisticalevidence for psychokinesis, that the evidence is generally of high methodological quality, and that effectsizes are distributed heterogeneously. Bo ¨sch et al. postulated the heterogeneity is attributable to selectivereporting and thus that psychokinesis is “not proven.” However, Bo ¨sch et al. assumed that effect size isentirely independent of sample size. For these experiments, this assumption is incorrect; it alsoguarantees heterogeneity. The authors maintain that selective reporting is an implausible explanation forthe observed data and hence that these studies provide evidence for a genuine psychokinetic effect.Keywords: meta-analysis, parapsychology, psychokinesis, random number generator