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Power and True Report Probability in the Literature on Mice Nicotine Conditioned Place Preference

  • Léonard, François
  • Tirelli, Ezio
Publication Date
May 28, 2021
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A lack of prospective power and use of effect sizes in the literature of various fields have been revealed and characterized over the years, giving rise to serious doubts on the reproducibility of many scientific results (Button & al. 2013, Nat.Rev.Neurosci. 14:365-376; Cohen 1962, Abnorm.Psychol. 65:145-153). To our knowledge, no study has address this problem in the field of experimental psychopharmacology using animal models. The articles were identified in PubMed. The sample size, the type of statistical test, its result, degrees of freedom and pvalue were recorded. We then computed the individual and the median prospective powers for 6 possible effect sizes (Cohen’s d: 0.01, 0.2, 0.5, 0.8, 1.2, 2). The TRP was computed from the median power, type-I error rate and the plausibility (prior probability). Amongst 139 articles, only 47 met our inclusion criteria for 109 statistical tests. In this sample, 77.57% of tests were significant. The median powers for small (0.2), medium (0.5) and large (0.8) effect sizes in F test were 9.56% [IQR 7.96%-11.5%], 34.45% [IQR 24.61%-47.01%] and 70.46% [IQR 52.92%-85.91%]. None of these numbers reached the recommended minimal prospective power of 80%. A 50% hypothetical plausibility yielded TRPs of 48.9%, 77.5%, and 87.6% for small, medium and large effect sizes. For a plausibility of 10%, the TRP were 16.1%, 40.8% and 58.5%. These results generalize to a subfield of animal-model experimental psychopharmacoloy (nicotine CPP in mice) the lack of power reported in the litterature of several neurobehavioural and psychological disciplines.

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