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January 30, 2015

January 30, 2015

Posted by **Lyn** on Friday, December 20, 2013 at 10:36pm.

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 mean a u=150 and a standard deviation of o=25. The mean of the sample 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 hypothesis (H0 and H1) for the two tailed test

d. Sketch the appropriate distribution and locate the critical region for a=.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.

- Statistics -
**PsyDAG**, Sunday, December 22, 2013 at 2:35ama. An

**independent variable**is the potential stimulus or cause, usually directly manipulated by the experimenter, so it could also be called a manipulative variable.

A**dependent variable**is the response or measure of results.

b. The training program will not change the test scores.

c. Ho: training test scores = non-training test scores

H1: training test scores ≠ non-training test scores

d. Cannot sketch on these posts.

e. With that small a sample, a t-test might be more appropriate.

Z = (sample mean-population mean)/SEm

SEm = SD/√n

Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion/probability related to the Z score.

f. From your results, you can make the decision.

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