Sample size to detect a significant difference between 2 means with unequal sample sizes and variances

Input Values


This utility calculates the sample size required to detect a statistically significant difference between two sample means with specified levels of confidence and power, assuming unequal variances and allowing for unequal sample sizes between groups.

Inputs are the assumed true values for the two means and their variances, the desired level of confidence and the desired power for the detection of a significant difference. By default, calculations assume that a two-tailed statistical test will be used, but a one-tailed test can also be specified if preferred.

The program outputs the sample size required to detect the specified difference with desired power and confidence, for a one-tailed or two-tailed statistical test, as specified.

Mean in population 1:
Variance in population 1:
Mean in population 2:
Variance in population 2:
Confidence level:
Ratio of sample sizes (n2/n1):
Use 1 or 2-tailed test: 1 tailed
  2 tailed


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