Two-sample hypothesis testing is a type of hypothesis testing which, instead of determining whether the value of a population parameter should or should not be rejected, determines whether the difference between the parameters of two populations is statistically significant.

Test Statistics

Two Sample t-Statistic

A two sample t-statistic is a test statistic for the population mean used when the population standard deviation is unknown but assumed to be the same for both populations and the sample size is small.

Where:

- Sample mean for the sample .
- Hypothesized population mean difference under the null hypothesis .
- Pooled standard deviation of the two samples.
- Sample size for the sample .