Hypothesis testing for the single population mean.
A researcher is investing the effectiveness of new study-skill training program for elementary school children. A sample of n = 25 third-grade children is selected to participate in the program and each child is given a standardized test at the end of the year. For the regular population of third-grade children, scores on the test form a normal distribution with mean of m = 150 and a standard deviation of s = 25. The mean of the sample is M = 158.
a. make out the independent and dependent variables for this study.
b. Assuming a two-tailed test, state the null hypothesis in a sentence that includes the independent variable and the dependent variable.
c. Using symbols state hypotheses (H_{0} and H_{1}) for the two-tailed test.
d. draw the appropriate distribution, and locate the critical region for a = 0.05.
e. compute the test statistic (z-score) for the sample.
f. What decision must be made about the null hypothesis, and what decision should be made about the effect of the program?