Question: The following data are from a research study comparing two treatment conditions. Do the data indicate a significant difference between treatments? Use a two-tailed test with α = .05.

a. For the first test, assume the data are from an independent-measures study using two separate samples.

b. For the second test, assume the data are from a repeated-measures study using the same sample of n = 5 participants in both treatments.

c. Explain why the 2-point mean difference is significant for one test but not for the other.

Treatment 1 Treatment 2
10 11
2 5
1 2
15 18
7 9
M = 7 M = 9
SS = 134 SS = 150