Statistical considerations
for study on the effect of one variable on another

Significance Level -- sided (default= .05, 2 sided).

Standard Deviation of the dependent variable, if known.

Standard Deviation of the independent variable, if known.

Enter two of the following three values and remaining value will be calculated.

  1. Power, usually .8 or .9.
  2. Total number of patients.
  3. Minimal detectable difference(Change in the dependent variable per unit change in the independent variable, If the standard deviations, above, are not known the units are "standard deviations")

Last Updated Nov, 21 1995
David A. Schoenfeld, Ph.D.,
With support from the Massachusetts General Hospital Mallinckrodt General Clinical Research Center, Research Resources Division, National Institutes of Health, General Clinical Research Center Program.