SPSS Analysis of Using General Linear Model – Univariate
The data are from an experiment run to evaluate the effect of solitary confinement on brain activity of
prisoners, i.e. frequency of brain waves. There are two factors of interest: the whole plot factor (Solitary
Confinement – 1 = “Yes”, 2 = “No”) and the subplot factor (Day – 1, 4, 7). The prisoners are repeatedly
measured on days 1, 4, and 7. There are four columns in the SPSS Data Table: Solitary, Prisoner, Day
and Frequency.
Solitary
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
1
1
1
Prisoner
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
1
2
3
Day
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
4
4
4
Frequency
14
24
21
20
15
17
16
10
6
32
20
16
15
20
14
13
4
22
21
13
7
16
10
M
M
M
M
2
2
2
18
19
20
7
7
7
21
22
14
You will need to use Analyze – General Linear Model – Univariate
• The Dependent Variable is Frequency.
• The Fixed Factors are Solitary and Day.
• A Random Factor is Prisoner.
• Click on Model and change Factorial to Custom.
• Use the Build Term(s) arrow to include Solitary, Prisoner, Day and Day*Solitary in your model.
The interaction term, Day*Solitary, can be included by highlighting both Day and Solitary under
Factors & Covariates and clicking on Build Term(s). Click on Continue.
• Click on Post Hoc and select LSD and put Solitary and Day under Post Hoc tests for. Click on
Continue.
• Click on OK.
1
The output from this analysis appears below.
Tests of Between-Subjects Effects
Dependent Variable: Frequency
Source
Intercept
Solitary
Prisoner
Day
Solitary * Day
Hypothesis
Error
Hypothesis
Error
Hypothesis
Error
Hypothesis
Error
Hypothesis
Error
Type I
Sum of
Squares
11426.40
0
1610.200
248.067
1610.200
1610.200
102.000
256.900
102.000
260.433
102.000
df
Mean Square
1
11426.400
18
1
18
18
36
2
36
2
36
89.456(a)
248.067
89.456(a)
89.456
2.833(b)
128.450
2.833(b)
130.217
2.833(b)
F
Sig.
127.733
.000
2.773
.113
31.573
.000
45.335
.000
45.959
.000
(a) MS(Prisoner)
(b) MS(Error)
Warnings
Post hoc tests are not performed for Solitary because there are fewer than three groups.
Multiple Comparisons
Dependent Variable: Frequency
LSD
Mean Difference
(J) Day
(I-J)
Std. Error
4.00
3.7000(*)
.53229
7.00
4.8500(*)
.53229
4.00
1.00
-3.7000(*)
.53229
7.00
1.1500(*)
.53229
7.00
1.00
-4.8500(*)
.53229
4.00
-1.1500(*)
.53229
Based on observed means.
* The mean difference is significant at the .05 level.
(I) Day
1.00
Sig.
.000
.000
.000
.037
.000
.037
95% Confidence Interval
2.6205
4.7795
3.7705
5.9295
-4.7795
-2.6205
.0705
2.2295
-5.9295
-3.7705
-2.2295
-.0705
2