Given the following information, calculate the degrees of freedom that should be used in the pooled-variance t test.
A) df = 41
B) df = 39
C) df = 16
D) df = 25

Question

Given the following information, calculate the degrees of freedom that should be used in the pooled-variance t test. 
A) df = 41 
B) df = 39 
C) df = 16 
D) df = 25

Quizplus · Accepted Answer

The pooled-variance t test formula uses the degrees of freedom from both samples. The formula is (s1^2/n1 + s2^2/n2)^2 / [(s1^2/n1)^2/(n1-1) + (s2^2/n2)^2/(n2-1)]. Given the sample sizes and sample variances of both groups, the calculation for degrees of freedom results in (14.47^2/15 + 21.08^2/25)^2 / [(14.47^2/15)^2/14 + (21.08^2/25)^2/24] which simplifies to 38.96. Rounded down to the nearest integer, the degrees of freedom to use in the pooled-variance t test is 39.

Given the Following Information, Calculate the Degrees of Freedom That