Question: A researcher is evaluating the influence of a treatment using a sample selected from a normally distributed population with a mean of µ = 80 and a standard deviation of ? = 20. The researcher expects a 12-point treatment effect and plans to use a two-tailed hypothesis test with α = .05.

a. Compute the power of the test if the researcher uses a sample of n = 16 individuals. (See Example 8.6.)

b. Compute the power of the test if the researcher uses a sample of n = 25 individuals.