Two separate samples are being used to estimate the population mean difference between two treatment conditions.Which of the following would produce the widest confidence interval?
A)n1 = n2 = 10 with a pooled variance of 10
B)n1 = n2 = 10 with a pooled variance of 100
C)n1 = n2 = 20 with a pooled variance of 10
D)n1 = n2 = 20 with a pooled variance of 100

Question

Quizplus · Accepted Answer

The width of a confidence interval for the difference between two means is influenced by both the sample sizes and the variances of the samples. A larger variance (pooled variance in this case) leads to a wider confidence interval. Among the options, the same sample sizes with a higher variance (option B: n1 = n2 = 10 with a pooled variance of 100) would produce the widest confidence interval.

Two Separate Samples Are Being Used to Estimate the Population