Effect Size Guidelines, Sample Size Calculations, and Statistical Power in Gerontology

Abstract

Cohen's guidelines appear to overestimate effect sizes in gerontology. Researchers are encouraged to use Pearson's <i>r</i> = .10, .20, and .30, and Cohen's <i>d</i> or Hedges' <i>g</i> = 0.15, 0.40, and 0.75 to interpret small, medium, and large effects in gerontology, and recruit larger samples.