The Welch-Satterthwaite t-test for two means has the same degrees of freedom as the pooled samples t-test for two means.

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Quizplus · Accepted Answer

The Welch-Satterthwaite t-test does not assume equal variances between the two groups, so the degrees of freedom are adjusted accordingly. The pooled samples t-test assumes equal variances, and thus has a different formula for degrees of freedom. Therefore, the degrees of freedom are not the same for both tests.

The Welch-Satterthwaite T-Test for Two Means Has the Same Degrees