About this resource

    Type of resources
    Primary Source, Reading, Paper
    Education level(s)
    College / Upper Division (Undergraduates)
    Primary user(s)
    Student
    Subject area(s)
    Math & Statistics
    Language(s)
    English
    Cluster
    Conceptual and Statistical Knowledge
    Last updated
    4 June 2020
    Primary SourceReadingPaper

    A Power Primer

    By Jacob Cohen

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    Level College / Upper Division (Undergraduates) · For Student · Language English

    Abstract

    One possible reason for the continued neglect of statistical power analysis in research in the behavioral sciences is the inaccessibility of or difficulty with the standard material. A convenient, although not comprehensive, presentation of required sample sizes is provided. Effect-size indexes and conventional values for these are given for operationally defined small, medium, and large effects. The sample sizes necessary for .80 power to detect effects at these levels are tabled for 8 standard statistical tests: (1) the difference between independent means, (2) the significance of a product–moment correlation, (3) the difference between independent rs, (4) the sign test, (5) the difference between independent proportions, (6) chi-square tests for goodness of fit and contingency tables, (7) 1-way analysis of variance (ANOVA), and (8) the significance of a multiple or multiple partial correlation.