Does psi exist? Reply to Storm and Ertel (2001)

The authors recently published a nonsignificant meta-analysis of 30 extrasensory perception ganzfeld studies, all conducted after the 1986 publication of important methodological guidelines aimed at reducing sources of artifact noted in earlier studies. In response, L. Storm and S. Ertel (2001) presented a meta-analysis of 79 studies published between 1974 and 1996. They argued that the positive and highly statistically significant overall outcome indicates a replicable paranormal effect. In doing so, they ignored the well-documented and widely recognized methodological problems in the early studies, which make it impossible to interpret the results as evidence of extrasensory perception. In addition, Storm and Ertel's meta-analysis is not an accurate quantitative summary of ganzfeld research because of methodological problems such as their use of an inconsistent method for calculating study outcomes and inconsistent inclusion criteria.