Meta-analysis of esp studies, 1987-2010: Assessing the success of the forced-choice design in parapsychology

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dc.contributor.authorStorm, L.
dc.contributor.authorTressoldi, P.
dc.contributor.authorDi Risio, L.
dc.date.issued2012
dc.description.abstractWe report the results of a meta-analysis on forced-choice ESP studies which used targets such as card symbols, numbers, letters, and so forth. For the period 1987 to 2010, a homogeneous dataset of 72 forced-choice studies yielded a weak but significant mean effect size (ES) of 0.01 (Stouffer Z = 4.86, p = 5.90 × 10 -7). There was no evidence that these results were due to low-quality design or selective reporting. The clairvoyance studies did not produce a significantly higher mean ES than the precognition studies, and target type did not make a difference to effect size. We note that effects do not vary between investigators, but we did find suggestive evidence that the number of choices per trial is inversely related to the p value. We also found evidence of a linear incline in ES values indicating that effect sizes have increased over the period 1987 to 2010. Suggestions are made that might help facilitate further increases in effect sizes.
dc.description.statementofresponsibilityLance Storm, Patrizio E. Tressoldi, and Lorenzo Di Risio
dc.identifier.citationJournal of Parapsychology, 2012; 76(2):243-273
dc.identifier.issn0022-3387
dc.identifier.orcidStorm, L. [0000-0002-6228-6150]
dc.identifier.urihttp://hdl.handle.net/2440/77864
dc.language.isoen
dc.publisherParapsychology Press Rhine Research Center
dc.rightsCOPYRIGHT 2012 Parapsychology Press
dc.source.urihttp://go.galegroup.com/ps/i.do?action=interpret&id=GALE%7CA320731642&v=2.1&it=r&p=AONE&sw=w&authCount=1
dc.subjectESP
dc.subjectforced-choice
dc.subjectmeta-analysis
dc.subjectparanormal
dc.subjectparapsychology
dc.subjectpsi
dc.titleMeta-analysis of esp studies, 1987-2010: Assessing the success of the forced-choice design in parapsychology
dc.typeJournal article
pubs.publication-statusPublished

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