Appraisal of Shawn Carlson’s Renowned Astrology Tests

Abstract

Shawn Carlson’s 1985 study, published in Nature, which ended with a devastating verdict of astrology, is scrutinized.  The design of Carlson’s study violated the demands of fairness and its mode of analysis ignored common norms of statistics.  The study’s piecemeal analysis of sub-samples avoided testing the totals for astrological effects, as did the neglect of test power, effect size, and sample size.  Nevertheless, a correct reanalysis of Carlson’s two astrological tests reveals that astrologers matched profiles of the California Personality Inventory to natal charts better than expected by chance with marginal significance (threeway forced choice, p = .054), and that a positive result was replicable by a different assessment method (10-point rating, p = .04). The results are regarded as insufficient to deem astrology as empirically verified, but they are sufficient to regard Carlson’s negative verdict on astrology as untenable