PSYCH/625 Time to Practice � Week Five - University of Phoenix Material
Week 5 practice exercises in psychological research methods.
Benjamin Clark
Contributor
4.8
50
about 1 month ago
Preview (3 of 9)
Sign in to access the full document!
Time to Practice – Week Five
PSYCH/625 Version 2
1
Copyright © 2014 by University of Phoenix. All rights reserved.
University of Phoenix Material
Time to Practice – Week Five
Complete Parts A, B, and C below.
Part A
Some questions in Part A require that you access data from Statistics for People Who (Think They) Hate
Statistics. This data is available on the student website under the Student Text Resources link.
1. Use the following data to answer Questions 1a and 1b.
Total no. of problems
correct (out of a possible
20)
Attitude toward test taking
(out of a possible 100)
17 94
13 73
12 59
15 80
16 93
14 85
16 66
16 79
18 77
19 91
a. Compute the Pearson product-moment correlation coefficient by hand and show all your work.
From the given data,
𝑛 = 10, 𝑥̅ = 15.6, 𝑦ത = 79.7, 𝑥𝑦 = 12568, 𝑥2 = 2476 𝑎𝑛𝑑 𝑦2 = 64727
Thus,
Correlation coefficient ( r ) = ∑ 𝑥𝑦−𝑛𝑥̅ 𝑦ത
ඥ(∑ 𝑥2−𝑛𝑥̅ 2)(∑ 𝑦2−𝑛𝑦2) = 0.5961
b. Construct a scatterplot for these 10 values by hand. Based on the scatterplot, would you predict
the correlation to be direct or indirect? Why?
The obtained scatter plot is as follows,
PSYCH/625 Version 2
1
Copyright © 2014 by University of Phoenix. All rights reserved.
University of Phoenix Material
Time to Practice – Week Five
Complete Parts A, B, and C below.
Part A
Some questions in Part A require that you access data from Statistics for People Who (Think They) Hate
Statistics. This data is available on the student website under the Student Text Resources link.
1. Use the following data to answer Questions 1a and 1b.
Total no. of problems
correct (out of a possible
20)
Attitude toward test taking
(out of a possible 100)
17 94
13 73
12 59
15 80
16 93
14 85
16 66
16 79
18 77
19 91
a. Compute the Pearson product-moment correlation coefficient by hand and show all your work.
From the given data,
𝑛 = 10, 𝑥̅ = 15.6, 𝑦ത = 79.7, 𝑥𝑦 = 12568, 𝑥2 = 2476 𝑎𝑛𝑑 𝑦2 = 64727
Thus,
Correlation coefficient ( r ) = ∑ 𝑥𝑦−𝑛𝑥̅ 𝑦ത
ඥ(∑ 𝑥2−𝑛𝑥̅ 2)(∑ 𝑦2−𝑛𝑦2) = 0.5961
b. Construct a scatterplot for these 10 values by hand. Based on the scatterplot, would you predict
the correlation to be direct or indirect? Why?
The obtained scatter plot is as follows,
Time to Practice – Week Five
PSYCH/625 Version 2
2
Copyright © 2014 by University of Phoenix. All rights reserved.
The scatter plot is indicating a non-linear pattern (quadratic) thus I would predict the correlation to
be indirect.
2. Rank the following correlation coefficients on strength of their relationship (list the weakest first):
+.71
+.36
–.45
.47
–.62
Answer is as follows.
0.36
-0.45
0.47
-0.62
0.71
3. Use IBM® SPSS® software to determine the correlation between hours of studying and grade point
average for these honor students. Why is the correlation so low?
Hours of studying GPA
23 3.95
12 3.90
15 4.00
14 3.76
PSYCH/625 Version 2
2
Copyright © 2014 by University of Phoenix. All rights reserved.
The scatter plot is indicating a non-linear pattern (quadratic) thus I would predict the correlation to
be indirect.
2. Rank the following correlation coefficients on strength of their relationship (list the weakest first):
+.71
+.36
–.45
.47
–.62
Answer is as follows.
0.36
-0.45
0.47
-0.62
0.71
3. Use IBM® SPSS® software to determine the correlation between hours of studying and grade point
average for these honor students. Why is the correlation so low?
Hours of studying GPA
23 3.95
12 3.90
15 4.00
14 3.76
Preview Mode
Sign in to access the full document!
100%
Study Now!
XY-Copilot AI
Unlimited Access
Secure Payment
Instant Access
24/7 Support
Document Chat
Document Details
University
University of Phoenix
Subject
Psychology