Sixteen S-squared over D-squared: a relation for crude sample size estimates

Stat Med. 1992 Jun 15;11(8):1099-102. doi: 10.1002/sim.4780110811.


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.

MeSH terms

  • Drug Evaluation*
  • Humans
  • Mathematics*
  • Research Design / standards*