Research note: Replicable evidence of PSI: a revision of Milton's (1999) meta-analysis of the Ganzfeld databases

Abstract

J. Milton (1999) found that D. J. Bem and C. Honorton's (1994) successful result of a significant mean effect size for a database of autoganzfeld studies had not been replicated, either by J. Milton and R. Wiseman's (1999) 30-study ganzfeld database or by all ganzfeld studies dating from 1987 to 1998 (which includes a further 9 ganzfeld studies deemed suitable for inclusion with Milton and Wiseman's 30 studies). D. Radin (cited in G. Schmeidler & H. Edge, 1999) found that Milton and Wiseman's database was indeed a successful replication of Bem and Honorton's meta-analysis. In deference to Milton, replications were in fact demonstrated by way of the same performance comparisons she made if 1 "extremely successful" study in Bem and Honorton's database is judiciously considered not suitable for inclusion in that database. The issues of database homogeneity and the "outlier problem" are raised.