Question: A researcher is investigating the effectiveness of a new study-skills 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 achievement test at the end of the year. For the regular population of third-grade children, scores on the test form a normal distribution with a mean of µ = 150 and a standard deviation of σ = 25. The mean for the sample is M = 158.

a. Identify the independent and the 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 the hypotheses (H0 and H1) for the two-tailed test.

d. Sketch the appropriate distribution, and locate the critical region for α = .05.

e. Calculate the test statistic (z-score) for the sample. f. What decision should be made about the null hypothesis, and what decision should be made about the effect of the program?