The earth is round (p < .05)

  title={The earth is round (p < .05)},
  author={Jacob Cohen},
  journal={American Psychologist},
  • Jacob Cohen
  • Published 1 December 1994
  • Psychology
  • American Psychologist
After 4 decades of severe criticism, the ritual of null hypothesis significance testing (mechanical dichotomous decisions around a sacred .05 criterion) still persists. This article reviews the problems with this practice, including near universal misinterpretation of p as the probability that H₀ is false, the misinterpretation that its complement is the probability of successful replication, and the mistaken assumption that if one rejects H₀ one thereby affirms the theory that led to the test… 

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