Sixteen S-squared over D-squared: a relation for crude sample size estimates.
I suggest for memorization an equation for calculating approximate sample size requirements intended only for a specific set of values (80 per cent power for a two-tailed alpha = 0.05 test) which seems to occur often in biopharmaceutical research. After presenting the formula in terms of variance estimate s2 and effect size d, I derive a few alternative forms and then discuss the accuracy of the approximation and other properties as well as examples of its use.
Lehr
R
R
Berlex Laboratories, Wayne, NJ 07470.
D004341:Drug Evaluation; D006801:Humans; D008433:Mathematics; D012107:Research Design / Q000592:standards*