PSYC 3000 Paired-Samples t-Test Lab
Data files are available on Canvas
Do NOT use the on-line calculator to calculate the effect size. Use the formula on the PPT to
calculate the effect size (Cohen’s d) for the paired-samples t-test.
Open the data file Paired-samples t-test File 1
1. Mike, a developmental psychologist, wants to know if overall life stress increases or
decreases as working women grow older. He obtains scores on the Index of Life Stress
(ILS) from a group of 100 working women when they are 40 years of age. He is able to
obtain a second set of ILS scores from 45 of these women at age 60 to assess whether
they felt significantly more or less stress as they grew older. The ILS consists of two
scores, interpersonal life stress and occupational life stress. The two scores combine to
form an index of overall life stress. The SPSS data file contains 45 case, one for each
woman, and four variables, their interpersonal and occupational life stress at age 40 and
their interpersonal and occupational life stress at age 60.
Compute the women’s scores to obtain a total Index of Life Stress (ILS) at age 40
and age 60.
Compute a paired-samples t-test to determine if overall life stress (ILS) scores, on
average, increases or decreases with age.
Create a difference variable to show the changes in ILS from 40 years of age to 60
years of age for each woman. Create a histogram to show these changes
graphically.
Mike decides that an overall ILS does not adequately reflect changes in women’s
life stress over time. He hypothesizes that occupational stress probably declines
as women get older, whereas interpersonal life stress may increase or stay the
same. Conduct a paired-samples t-test to evaluate Mike’s hypotheses.
Answer the questions below based on the analyses you just conducted. Make an
APA style table to report the results based on your analyses in exercises a
through d above.
a. Paste the data for the two new variables below
ILS_40 ILS_60
145 148
166 139
171 143
155 123
165 132
129 140
116 147
151 144
166 138
167 141
146 134
164 150
, 163 157
170 140
135 127
154 133
167 134
153 159
153 137
170 134
153 128
162 154
159 121
166 130
173 149
148 128
169 120
133 134
153 144
161 128
135 135
147 155
145 130
147 130
122 125
156 138
154 145
143 132
148 125
139 138
126 151
132 135
133 128
160 125
163 131
Does interpersonal life stress increase or The mean interpersonal life stress decreased from
decrease with age? 78.20 at age 40 to 75.00 at age 60.
What is the mean difference between The interpersonal life stress decreased by 3.20 points
interpersonal life stress at 40 and at 60? on average as women aged from 40 to 60.
Is this a significant difference? Why or The difference is not a significant because the paired-
why not? samples t-test yielded t(44) = 1.54, p = .131. Since
the p-value (.131) is greater than the conventional
alpha level of .05, we fail to reject the null
hypothesis. This means that the small decrease in
interpersonal life stress from age 40 to age 60 is not
Data files are available on Canvas
Do NOT use the on-line calculator to calculate the effect size. Use the formula on the PPT to
calculate the effect size (Cohen’s d) for the paired-samples t-test.
Open the data file Paired-samples t-test File 1
1. Mike, a developmental psychologist, wants to know if overall life stress increases or
decreases as working women grow older. He obtains scores on the Index of Life Stress
(ILS) from a group of 100 working women when they are 40 years of age. He is able to
obtain a second set of ILS scores from 45 of these women at age 60 to assess whether
they felt significantly more or less stress as they grew older. The ILS consists of two
scores, interpersonal life stress and occupational life stress. The two scores combine to
form an index of overall life stress. The SPSS data file contains 45 case, one for each
woman, and four variables, their interpersonal and occupational life stress at age 40 and
their interpersonal and occupational life stress at age 60.
Compute the women’s scores to obtain a total Index of Life Stress (ILS) at age 40
and age 60.
Compute a paired-samples t-test to determine if overall life stress (ILS) scores, on
average, increases or decreases with age.
Create a difference variable to show the changes in ILS from 40 years of age to 60
years of age for each woman. Create a histogram to show these changes
graphically.
Mike decides that an overall ILS does not adequately reflect changes in women’s
life stress over time. He hypothesizes that occupational stress probably declines
as women get older, whereas interpersonal life stress may increase or stay the
same. Conduct a paired-samples t-test to evaluate Mike’s hypotheses.
Answer the questions below based on the analyses you just conducted. Make an
APA style table to report the results based on your analyses in exercises a
through d above.
a. Paste the data for the two new variables below
ILS_40 ILS_60
145 148
166 139
171 143
155 123
165 132
129 140
116 147
151 144
166 138
167 141
146 134
164 150
, 163 157
170 140
135 127
154 133
167 134
153 159
153 137
170 134
153 128
162 154
159 121
166 130
173 149
148 128
169 120
133 134
153 144
161 128
135 135
147 155
145 130
147 130
122 125
156 138
154 145
143 132
148 125
139 138
126 151
132 135
133 128
160 125
163 131
Does interpersonal life stress increase or The mean interpersonal life stress decreased from
decrease with age? 78.20 at age 40 to 75.00 at age 60.
What is the mean difference between The interpersonal life stress decreased by 3.20 points
interpersonal life stress at 40 and at 60? on average as women aged from 40 to 60.
Is this a significant difference? Why or The difference is not a significant because the paired-
why not? samples t-test yielded t(44) = 1.54, p = .131. Since
the p-value (.131) is greater than the conventional
alpha level of .05, we fail to reject the null
hypothesis. This means that the small decrease in
interpersonal life stress from age 40 to age 60 is not
