In the independent groups t test an average of s 12 and s 22 , weighted by the degrees of freedom, is used to estimate s 2 .

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Quizplus · Accepted Answer

This statement is true. The formula for the estimated standard error of the difference between means in the independent groups t test is SED = sqrt [(s12/n1) + (s22/n2)]. To estimate the variance of the difference between means, s2, this formula is squared, which results in s2 = [(s12/n1) + (s22/n2)] * (df1 + df2)/(df1df2). Since this formula involves both s12 and s22, they must be combined in some way to estimate s2. The average of s12 and s22, weighted by their degrees of freedom (df1 and df2), is used for this estimation.

In the Independent Groups T Test an Average of S