Problems
We wish to test the null hypothesis that a mean equals 100
against an alternative that it is greater than 100. We will
estimate power based on the specific alternative that the mean
equals 105. The population standard deviation equals 20. The
sample size is 25.
a. What part of the null distribution contains the rejection
region?
b. What is the z score for alpha = .05?
c. Convert the z score to a score based on a mean of 100 and the
appropriate standard error.
d. What is the power of the test?
2. Repeat problem 1 for n = 100.
3. Repeat problem 1 for the alternative hypothesis that the mean
equals 90.
Answer
1. Solve for the sample size required for the following
combinations of type I error and power. Use the information
given in problem one for objective 21.