Library / The Earth is Round (p < .05)


Jacob Cohen “The earth is round (p < .05)” (1994) // American Psychologist. Publisher: American Psychological Association (APA). Vol. 49. No 12. Pp. 997–1003. DOI: 10.1037/0003-066x.49.12.997


  title = {The earth is round (p &lt; .05)},
  volume = {49},
  issn = {0003-066X},
  url = {},
  doi = {10.1037/0003-066x.49.12.997},
  number = {12},
  journal = {American Psychologist},
  publisher = {American Psychological Association (APA)},
  author = {Cohen, Jacob},
  year = {1994},
  month = {dec},
  pages = {997–1003}

Quotes (4)


What’s wrong with NHST? Well, among many other things, it does not tell us what we want to know, and we so much want to know what we want to know that, out of desperation, we nevertheless believe that it does!

Page 997

The Null Hypothesis Ritual

After 4 decades of severe criticism, the ritual of null hypothesis significance testing — mechanical dichotomous decisions around a sacred .05 criterion — still persists.

Page 997

The Illusion of Attaining Improbability

One problem arises from a misapplication of deductive syllogistic reasoning. Falk and Greenbaum (in press) called this the “illusion of probabilistic proof by contradiction” or the “illusion of attaining improbability.” Gigerenzer (1993) called it the “permanent illusion” and the “Bayesian Id’s wishful thinking,” part of the “hybrid logic” of contemporary statistical inference—a mishmash of Fisher and Neyman-Pearson, with invalid Bayesian interpretation.

Page 998

Embarrassignly Large Confidence Intervals

“Everyone knows” that confidence intervals contain all the information to be found in significance tests and much more. They not only reveal the status of the trivial nil hypothesis but also about the status of non-nil null hypotheses and thus help remind researchers about the possible operation of the crud factor. Yet they are rarely to be found in the literature. I suspect that the main reason they are not reported is that they are so embarrassingly large!

Page 1002