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

The test statistic is:

[math]\displaystyle{ t = \frac{\bar{x} - \bar{y}}{s \sqrt{\frac{1}{m} + \frac{1}{m}}} }[/math]

where:

[math]\displaystyle{ \bar{x} }[/math] and [math]\displaystyle{ \bar{x} }[/math] are the average values of variables [math]\displaystyle{ x }[/math] and [math]\displaystyle{ y }[/math] respectively, where each of these variables represents the data from two independent groups,

the groups have sample sizes of [math]\displaystyle{ m }[/math] and [math]\displaystyle{ n }[/math] respectively,

[math]\displaystyle{ s = \sqrt{d_{eff}\frac{(m-1)s^2_x + (m-1)s^2_y }{m + n - 2b}} }[/math],

[math]\displaystyle{ b }[/math] is 1 if Bessel's correction for Means is selected in Statistical Assumptions and 0 otherwise,

[math]\displaystyle{ s^2_x }[/math] and [math]\displaystyle{ s^2_y }[/math] are the sample variances in the two groups,

[math]\displaystyle{ d_{eff} }[/math] is Extra Deff.

[math]\displaystyle{ p = 2\Pr(t_{n+m-2} \ge |t|) }[/math]