PSYC 354 Homework 7 Liberty University

Homework 7

Confidence Intervals, Effect Size, and Statistical Power

Be sure you have reviewed this module/week’s lessons and presentations along with the practice data analysis before proceeding to the homework exercises. Complete all analyses in SPSS, then copy and paste your output and graphs into your homework document file. Number all responses. Answer any written questions (such as the text-based questions or the APA Participants section) in the appropriate place within the same file. Review the “Homework Instructions: General” document for an example of how homework assignments must look.

Part I: Concepts

1.     Fill in the blanks with the correct word or words.

a.     The confidence interval is centered around the _____ of the sample.

b.     Cohen's d measures the difference between means in terms of _______.

c.     According to Cohen's conventions, a d value of _______ indicates a large effect.

d.     A study that calculates the mean effect size from the individual effect sizes of many studies is called a(n) _______.

e.     Statistical power refers to the probability of successfully rejecting the _______.

Complete the following Nolan and Heinzen end-of-chapter exercises for Chapter 8: 8.15, 8.22, 8.26, and 8.40. If applicable, remember to show work in your homework document to receive partial credit

Compute effect size in the following questions:

1.     A company decides to add a new program that prepares randomly selected sales personnel to increase their number of sales per month. The mean number of sales per month for the overall population of sales personnel at this national company is 25 with a standard deviation of 4. The mean number of sales per month for those who participated in the new program is 29. Compute the effect size of the new sales program. 

2.     On a certain anxiety questionnaire, the population is known to have a mean of 12 and a standard deviation of 2.3. A higher score represents higher levels of anxiety. Participants in a new relaxation program complete the questionnaire after completing the program and have a mean score of 10.2. What is the effect size of the relaxation program?

3.     A residential treatment facility tests a new group therapy for patients with self-destructive behaviors. The therapists hope to decrease scores on a measure of self-destructive behaviors that has a mean in the overall residential treatment population of 35 and a standard deviation of 4.7. The mean score for the patients after the new group therapy is 27. What is the effect size of the new group therapy? 

Parts II and III: There is no new SPSS material this module/week