Sample size calculator

Distributions: Normal, T

one varaince test tutorial


t distribution left tailed t distribution two tailed t distribution right tailed

Test calculation

Calculate the sample size to gain the required test power and draw a power analysis chart.

Use this test for one of the following tests:
One Sample Z-Test
One Sample T-Test
Two Sample Z-Test
Two Sample T-Test (Pooled variance)
Two Sample T-Test (Welch's) - only approximation

Statistic Data

digits: example digits=2: (0.001234 => 0.0012)
α: significant level (0-1), maximum chance allowed rejecting H0 while H0 is correct (Type1 Error)
power: required test power
The power is expected to identify the effect. If one exists, H0 will be rejected. effect size (standardized) - the change the test is expected to identify
standardized effect size - the change divided by the standard deviation. examples:
0.2 - small effect, 0.5 - medium , 0.8 - large
σ1: standard deviation
σ2: standard deviation

validation message