Independent Samples t-Test - Comparing Two Means with Equal Variances

The test statistic is:

$t=\frac{\overline{x}-\overline{y}}{s\sqrt{\frac{1}{m}+\frac{1}{m}}}$

where:

$\overline{x}$ and $\overline{x}$ are the average values of variables $x$ and $y$ respectively, where each of these variables represents the data from two independent groups,

the groups have sample sizes of $m$ and $n$ respectively,

$s=\sqrt{d_{eff}\frac{(m-1)s_x^2+(m-1)s_y^2}{m+n-2b}}$,

$b$ is 1 if Bessel's correction for Means is selected in Statistical Assumptions and 0 otherwise,

$s_x^2$ and $s_y^2$ are the sample variances in the two groups,

$d_{eff}$ is Extra Deff.

$p=2\mathrm{Pr}(t_{n+m-2}\ge |t|)$