In testing the difference between the means of two normally distributed populations, the number of degrees of freedom associated with the unequal-variances t-test statistic usually results in a non-integer number. It is recommended that you: A) round up to the nearest integer B) round down to the nearest integer C) change the sample sizes until the number of degrees of freedom becomes an integer D) assume that the population variances are equal, and then use df = n₁ + n₂-2 E) assume that the population variances are equal, and then use df = z₁ + z₂-2

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When calculating the degrees of freedom for an unequal-variances t-test (also known as Welch's t-test), the resulting number often is a non-integer. The common practice is to round this number to the nearest integer to simplify the analysis, and rounding up is recommended to be more conservative in statistical testing.

In Testing the Difference Between the Means of Two Normally