Minimum Sample Size Calculator
Calculate the minimum sample size needed to achieve desired statistical power for various types of hypothesis tests.
Test Parameters
0.2 (small)0.5 (medium)0.8 (large)
Minimum Sample Size
32
One-sample t-test
Effect Size
0.5
Medium
Power
80%
Critical Values:
Z (alpha):
1.960
Z (power):
0.842
Alpha:
0.05
Minimum Sample Size for Power
This calculator determines the minimum number of observations needed to detect an effect of a given size with specified statistical power. Using too few subjects may result in a study that cannot detect real effects (Type II error), while using too many wastes resources.
Effect Size Guidelines
Small: 0.2
Subtle effect
Medium: 0.5
Visible effect
Large: 0.8
Obvious effect