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Two-Sample T-Test Calculator
Sample size and power for independent group comparisons (Welch’s t-test)
Sample Size
Power
Statistical Power
Alpha (Type I Error)
Mean of Group 1
SD of Group 1
Mean of Group 2
SD of Group 2
Group 2 / Group 1 Size Ratio
Test Type
Two-sided
One-sided
Calculate Sample Size
Results
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Mean of Group 1
SD of Group 1
Mean of Group 2
SD of Group 2
Group 1 Sample Size
Group 2 Sample Size
Alpha (Type I Error)
Test Type
Two-sided
One-sided
Calculate Power
Results
Copy