# PSYC Statistics, homework 4

Note: The z-scoring method used in the practice data file is covered in Lesson 19 during PSYC 354.

Green & Salkind: Lesson 33, Exercises 1, 3–4

The following helpful tips are numbered to correspond with the exercise number to which they refer (a dash indicates that no tips are needed):

1. Though the example in the lesson includes creating a z score variable, this step is not necessary for the homework exercises. (3 pts for output and 3 pts each for a–e)

3. Write the answer to the last part of this question beneath your graph, in sentence form. (3 pts)

4. All homework “Results sections” must follow the example given in the Course Content document “Writing Results of Statistical Tests in Current APA Format” (Note: you do not have to refer to a figure). Note: The statistical statement for a bivariate linear regression must include at least the equation of the line and the confidence interval for the slope (the second row under Confidence Intervals in the output). (3 pts)

Part 2:

1. A community psychologist is interested in whether spending time in after-school programs is predictive of the number of arrests as a young adult in a high-risk neighborhood. After collecting records on 17 individuals over 8 years, the psychologist compiles the information listed in the table below. Conduct a linear regression to analyze the research question.

The steps will be the same as the ones you have been practicing in Part 1 of the assignment—the only difference is that you are now responsible for creating the data file as well. Remember to name and define your variables under the “Variable View,” then return to the “Data View” to enter the data. (3 pts)

Table is shown on the following page.

Hours Spent in After-School Programs

Number of Arrests After Age 17

3

2

41

1

68

1

29

0

7

5

12

4

121

0

54

1

19

3

134

0

106

1

67

1

25

3

73

1

38

4

110

0

31

3

2. Construct a scatterplot of the relationship between the 2 variables. Plot the regression line on this graph. (3 pts)

3. Is time spent in after-school programs predictive of the number of arrests as a young adult? Write a Results section in current APA style describing the outcome. All homework “Results sections” must follow the example given in the Course Content document “Writing Results of Statistical Tests in Current APA Format” (Note: you do not have to refer to a figure). The statistical statement for a bivariate linear regression must include at least the equation of the line and the confidence interval for the slope (the second row under Confidence Intervals in the output). (3 pts)

Part 3: Cumulative Homework

1. To investigate the relationship between hours spent studying and exam scores, researchers measured the following. Is there a significant relationship between hours spent studying and scores? Choose the correct test to analyze this question, set up the SPSS file, and run the analysis. Follow the directions under the table on the following page.

Hours Spent Studying

Exam Scores 1

3

3

4

4

5

5

5

6

6

7

7

8 40

50

51

61

73

71

64

75

68

76

94

85

84

a) Paste appropriate SPSS output. (3 pts)

b) Paste appropriate SPSS graph. (3 pts)

c) Write a Results section in current APA style describing the outcome. All homework “Results sections” must follow the example given in the Course Content document “Writing Results of Statistical Tests in Current APA Format” (Note: you do not have to refer to a figure). (4 pts)

Submit this assignment by 11:59 p.m. (ET) on Monday of Module/Week 6.