For each of the following, calculate the pooled variance and the estimated standard error for the sample mean difference

a. The first sample has n 5 4 scores and a variance of s

2 5 17, and the second sample has n 5 8 scores and a variance of s 2 5 27.

b. Now the sample variances are increased so that the first sample has n 5 4 scores and a variance of s

2 5 68, and the second sample has n 5 8 scores and a variance of s 2 5 108.

c. Comparing your answers for Parts a and

b, how does increased variance influence the size of the estimated standard error?