PSYC 355
SPSS Homework: Paired-Samples t Test Assignment
Katherine Crisco
School of Behavioral Science, Liberty University
PSYC 355: Statistics in Psychology
Dr. Haynes
September 1, 2025
Problem Set 1: The paired-samples t test
Research Scenario: Research Scenario: A researcher is interested in how pairs of identical twins
score on the Verbal SAT in late high school. She collects scores from 11 twin pairs (related
subjects). The data appear in the table below.
Using this table, enter the data into a new SPSS data file and run a paired-samples t test to
test the claim that twins score differently from one another on the Verbal SAT. Remember to
put your initials within any and all variable names. Create a boxplot to show the difference
between the groups. Follow the directions below the table to complete this part.
Twin 1 Twin 2
630
577
698
409
499
659
617
683
702
590
502
621
503
723
450
474
701
634
656
723
684
650
1. Paste SPSS output. (10 pts)
PSYC 355
Paired Samples Statistics
Mean N
Std. Deviation Std. Error
Mean
Pair 1 Twin 1Verbal SAT Score 596.91 11 94.009 28.345
Twin 2 Verbal SAT Score 619.91 11 99.082 29.874
Paired Samples Test
Paired DifferencestdSignifica fnce
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2. Write an APA-style Results section based on your analysis. Include your boxplot as an
APA-style Figure, with figure number and title, as demonstrated in the Results Section
presentation. (Results = 12 pts; Figure = 8 pts)
Results
A repeated t-test was done, and it was used to measure and determine whether the SAT final
scores were differed between identical twin sisters and brothers. The final results conveyed that
the SAT scores were not different between twin ones which was M=596.9 and SD= 94.0, and it
was compared with twin two, which was M=61.99 and SD=99.0. The t-test was t (10)=-1.26 and
p=.236, and it was two-tailed. The scores can be seen below in the Box plot. In the end, the test
fails to reject the null hypothesis that there is no big difference between the twins’ SAT final
scores
Case Processing Summary
Cases
Valid Missing Total
N Percent N Percent N Percent
PSYC 355
Twin 1Verbal SAT Score 11 100.0% 0 0.0% 11 100.0%
Twin 2 Verbal SAT Score 11 100.0% 0 0.0% 11 100.0%
CONTINUED ON NEXT PAGE
Problem Set 2: The paired-samples t test
Research Scenario: A clinical psychologist is studying whether keeping a gratitude journal
decreases self-reported depression in high-school females. She administers the Beck Depression
Inventory (BDI; Beck et al., 1961) and selects 10 female students with scores greater than 20.
She then gives each of these participants a journal with instructions on how to keep a daily
record of people, events, and other things that they are thankful for, After one month of
journaling, the participants complete the BDI a second time. The data are given in the table
below.
Using this table, enter the data into a new SPSS data file and run a paired-samples t test to
test the claim that keeping a gratitude journal decreases self-reported depression in
highschool females. Remember to put your initials within any and all variable names. Create a
boxplot to show the difference between the groups. Follow the directions below the table to
complete this part.
BDI Scores Before
Journal
BDI Scores After
Journal
21
21
29
25
32
40
24
42
26
22
19
8
31
22
26
36
24
33
10
16
1. Paste SPSS output. (10 pts)
Paired Samples Statistics
Mean N
Std. Deviation Std. Error
Mean
Pair 1 BDI Pre-Journaling 28.20 10 7.598 2.403
BDI Post- 22.50 10 9.431 2.982
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PSYC 355
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PSYC 355
2. Write an APA-style Results section based on your analysis. Include your boxplot as an
APA-style Figure, with figure number and title, as demonstrated in the Results Section
presentation. (Results = 12 pts; Figure = 8 pts)
Results
A t-test was done repeatedly, and it was run to see and to determine if keeping a journal
full of gratitude would ultimately decrease self-reported depression in high school-aged
female students on the BDI scale. The final results conveyed that the scores on the BDI
scale hugely decreased from before the female students wrote in the journal, which was
M=28.2 and SD=7.6. This was fully compared with the one-month-long writing in the
journal, which was M=22.5 and SD=9.4, and the t-test was t(9)-320 and p=.005, and it
was shown that it was one-tailed. Given the scores below in the box plot, it would
ultimately reject the null hypothesis that there is no decrease in the depression, using
the BDI scores, even after using the journal that was full of gratitude.
Case Processing Summary
Cases
Valid Missing Total
PSYC 355
N Percent N Percent N Percent
BDI Pre-Journaling 10 100.0% 0 0.0% 10 100.0%
BDI Post-Journaling 10 100.0% 0 0.0% 10 100.0%
Problem Set 3: Cumulative Knowledge Question
Research Scenario: An industrial/organizational psychologist at a large financial company wants
to compare the morale of employees who work in person vs. remotely. For his first study, he
chooses members of a team that handle customer complaints. He sends a survey designed to
measure employee morale to 12 team members in each group. The data appear in the table
below.
Using this table, enter the data into a new SPSS data file. Choose and run the correct analysis
(it will be one learned in a previous module) to determine whether there is a difference in
employee morale between the two groups. Choose and create the correct graph that
corresponds with this analysis. Remember to put your initials within any and all variable
names. Follow the directions below the table to complete this part.
1. Paste SPSS output. (10 pts)
2.
3. Write an APA-style Results section based on your analysis. Include the correct graph as
an APA-style Figure, with figure number and title, as demonstrated in the Results Section
presentation. (Results = 12 pts; Figure = 8 pts) Results
A repeated t-test was done and it was done to find out and to essentially determine if
there was some type of difference in employee morale between the employees who worked on
site and the employees who worked at home. The final results showed that the morale score did
not show a big difference between the two, which was the people who worked on site, which
was M=29.5 and SD=10.4, and this was compared to the people who worked at home, which
PSYC 355
was M=24.4 and SD=10.7. The t-test was t(70=.934 and p=.381 and it was two-tailed. The scores
below can be seen in a boxplot showing that there is not a big difference between the two.
Case Processing Summary
Cases
Valid Missing Total
N Percent N Percent N Percent
Work Location 8 100.0% 0 0.0% 8 100.0%
Employee Morale 8 100.0% 0 0.0% 8 100.0%
