Correcting for multiple comparisons in studies of dream content: A statistical addition to the Hall/Van de Castle coding system.

Abstract

University of California, Santa CruzThis article addresses the issue of potential false positives when multiple tests arecarried out in comparing 2 samples with the content indicators used in the Hall andVan de Castle (1966) coding system for dream content. Using an algorithm based onthe Benjamini–Hochberg (Benjamini & Hochberg, 1995) correction for the FalseDiscovery Rate, it first compares findings for men and women in a large normativesample; all 12 of the statistically significant differences at the .05 level remain, alongwith 10 of 11 below .01. The article then compares results from an individual’s dreamseries with the norms for women; 10 of the 12 significant p values at the .05 levelremain, along with 4 of 5 below .01. The article concludes that earlier findings withthe Hall-Van de Castle system can be viewed as established findings, and recom-mends that the correction formula be used with large samples.