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 = 4 scores and a variance of s2 = 55, and the second sample has n = 6 scores and a variance of s2 = 63.
b. Now the sample variances are increased so that the first sample has n = 4 scores and a variance of s2 = 220, and the second sample has n = 6 scores and a variance of s2 = 252.
c. Comparing your answers for parts a and b, how does increased variance influence the size of the estimated standard error?