An Interactive Tutorial for SPSS 10.0 for Windows©
Factorial
Analysis of Variance
by
Julia Hartman
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© Copyright 2000, Julia Hartman
1
Factorial ANOVA:
Introduction
In this tutorial, Factorial Analysis of Variance
(ANOVA) will be used to determine whether
gender and residency location interact to affect
scores on the US Medical Licensing Exam
(Part 2) scores.
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2
Factorial ANOVA:
Introduction
• Independent variables (fixed factors)
 gender: Gender of student (1 = female, 2 = male)
 resloc: Residency location
(1 = in-state, 2 = out of state)
• Dependent variable
 usmle2: USMLE Step 2 (continuous)
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3
Factorial ANOVA:
Starting the Procedure
• In the menu, click
Analyze
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4
Factorial ANOVA:
Starting the Procedure
• In the menu, click on
Analyze
• Point to
General Linear Model
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5
Factorial ANOVA:
Starting the Procedure
• In the menu, click on
Analyze
• Point to
General Linear Model
• Point to Univariate…
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6
Factorial ANOVA:
Starting the Procedure
• In the menu, click on
Analyze
• Point to
General Linear Model
• Point to Univariate…
… and click.
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7
Factorial ANOVA:
Selecting Variables
Choose the variables
for analysis from the
list in the variable
box.
For this tutorial,
begin by pointing to
the variable labeled
GENDER OF STUDENT
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8
Factorial ANOVA:
Selecting Variables
Choose the variables
for analysis from the
list in the variable
box.
For this tutorial,
begin by pointing to
the variable labeled
GENDER OF STUDENT
…and click.
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9
Factorial ANOVA:
Selecting Variables
Move gender, a
categorical variable, to
the box labeled
Fixed Factor(s) by
clicking the arrow.
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10
Factorial ANOVA:
Selecting Variables
Scroll down the list,
point to the variable
resloc, which is labeled
RESIDENCY LOCATION,
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11
Factorial ANOVA:
Selecting Variables
Scroll down the list,
point to the variable
resloc, which is labeled
RESIDENCY LOCATION,
…and click.
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12
Factorial ANOVA:
Selecting Variables
Move resloc, another
categorical variable, to
the box labeled
Fixed Factor(s) by
clicking the arrow.
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13
Factorial ANOVA:
Selecting Variables
Scroll further down
the list and point to
the variable usmle2,
which is labeled
USMLE STEP 2,
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14
Factorial ANOVA:
Selecting Variables
Scroll further down
the list and point to
the variable usmle2,
which is labeled
USMLE STEP 2 TOTAL,
…and click.
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15
Factorial ANOVA:
Selecting Variables
Move usmle2, a
continuous variable, to
the box labeled
Dependent Variable by
clicking the arrow.
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16
Factorial ANOVA:
Tutorial Options
The Univariate GLM
procedure offers a
number of options.
Click this button
for a list of the options
included in this tutorial.
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17
Factorial ANOVA:
List of Tutorial Options
Click the box for the desired option.
• Profile plots of estimated
marginal means
• Post hoc tests for pairwise
multiple comparisons
• Optional descriptive and
diagnostic statistics
• Continue with the analysis
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18
Factorial ANOVA:
List of Tutorial Options
Click the box for the desired option.
• Profile plots of estimated
marginal means
• Post hoc tests for pairwise
multiple comparisons
• Optional descriptive and
diagnostic statistics
• Continue with the analysis
© Copyright 2000, Julia Hartman
19
Factorial ANOVA:
List of Tutorial Options
Click the box for the desired option.
• Profile plots of estimated
marginal means
• Post hoc tests for pairwise
multiple comparisons
• Optional descriptive and
diagnostic statistics
• Continue with the analysis
© Copyright 2000, Julia Hartman
20
Factorial ANOVA:
List of Tutorial Options
Click the box for the desired option.
• Profile plots of estimated
marginal means
• Post hoc tests for pairwise
multiple comparisons
• Optional descriptive and
diagnostic statistics
• Continue with the analysis
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21
Factorial ANOVA:
Profile Plots
Request profile plots
of estimated marginal
means by clicking the
button labeled
Plots…
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22
Factorial ANOVA:
Profile Plots
This tutorial requests
both available profile
plots, gender*resloc
and resloc*gender.
Click gender in the
Factors box.
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23
Factorial ANOVA:
Profile Plots
Move gender to the
Horizontal Axis box by
clicking the arrow.
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24
Factorial ANOVA:
Profile Plots
Now click resloc in
the Factors box …
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25
Factorial ANOVA:
Profile Plots
and move it to the
Separate Lines box
by clicking the arrow.
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26
Factorial ANOVA:
Profile Plots
Click the Add button
to request the plot.
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27
Factorial ANOVA:
Profile Plots
To request the plot of
resloc*gender,
click resloc in the
Factors box.
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28
Factorial ANOVA:
Profile Plots
Move resloc to the
Horizontal Axis box by
clicking the arrow.
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29
Factorial ANOVA:
Profile Plots
Now click gender in
the Factors box…
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30
Factorial ANOVA:
Profile Plots
…and move it to the
Separate Lines box
by clicking the arrow.
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31
Factorial ANOVA:
Profile Plots
Click the Add button
to request the plot.
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32
Factorial ANOVA:
Profile Plots
Click the Continue
button.
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33
Factorial ANOVA:
Post Hoc Multiple Comparisons
To request post hoc
tests for pairwise
multiple comparisons,
click the Post Hoc…
button.
(The factors in this analysis-gender and resloc--each
have only two categories, so
post hoc option is explained
only for tutorial purposes.)
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34
Factorial ANOVA:
Post Hoc Multiple Comparisons
This example
requests tests for
gender only.
Click gender in the
Factor(s) box.
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35
Factorial ANOVA:
Post Hoc Multiple Comparisons
Move gender to the
Post Hoc Tests for:
box by clicking the
arrow.
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36
Factorial ANOVA:
Post Hoc Multiple Comparisons
Request multiple
comparison test(s) by
clicking in the
corresponding
checkbox.
For this tutorial,
click Bonferroni.
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37
Factorial ANOVA:
Post Hoc Multiple Comparisons
In SPSS, you can
request as many
multiple comparison
tests as you want.
To continue the
tutorial, click the
Continue button.
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38
Factorial ANOVA:
Optional Descriptive and
Diagnostic Statistics
To display estimated
marginal means,
parameter estimates,
and descriptive and
diagnostic statistics,
and or to change the
alpha level, click the
Options… button.
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39
Factorial ANOVA:
Options: Estimated Marginal Means
You can request an overall
(grand) marginal mean, as
well as marginal means
for the factors and the
interaction(s).
To select all of these at
once, first click
[OVERALL] .
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40
Factorial ANOVA:
Options: Estimated Marginal Means
Hold the Shift key (on the
keyboard) and click
gender*resloc to select the
entire list.
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41
Factorial ANOVA:
Options: Estimated Marginal Means
Click the arrow to move
the factors and factor
interaction terms to the
Display Means for: box.
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42
Factorial ANOVA:
Options: Estimated Marginal Means
In SPSS, you can display
information by rightclicking, but rightclicking doesn’t work in
this tutorial.
To see what right-clicking
would show, left-click
Compare main effects.
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43
Factorial ANOVA:
Options: Estimated Marginal Means
Click the checkbox for
Compare main effects.
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44
Factorial ANOVA:
Options: Estimated Marginal Means
You can change the
method used for
confidence interval
adjustments by selecting
from the drop-down list.
Click the drop-down
arrow for Confidence
interval adjustment.
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45
Factorial ANOVA:
Options: Estimated Marginal Means
This tutorial will use the
default method, so click
elsewhere on the
window to close the
drop-down menu.
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46
Factorial ANOVA:
Selecting Options
Request other options by
clicking the appropriate
checkbox.
In the Display area, click
the checkbox for
Descriptive statistics…
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47
Factorial ANOVA:
Selecting Options
…and the one for
Homogeneity tests.
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48
Factorial ANOVA:
Selecting Options
This tutorial uses no more
options, so click the
Continue button.
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49
Factorial ANOVA:
Run the analysis
Click the OK button to
run the Factorial
ANOVA.
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50
Factorial ANOVA Output:
Warnings and General Information
The labels and format
of your output may be
somewhat different.
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51
Factorial ANOVA Output: :
Descriptive Statistics
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52
Factorial ANOVA Output:
Test of Equality of Error Variances
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53
Factorial ANOVA Output:
Tests of Between-Subjects Effects
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54
Factorial ANOVA Output:
Estimated Marginal Means:
Grand Mean
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55
Factorial ANOVA:
Gender: Estimated Marginal Means
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56
Factorial ANOVA:
Gender: Pairwise Comparisons
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57
Factorial ANOVA:
Gender: Univariate Tests
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58
Factorial ANOVA:
Resloc: Estimated Marginal Means
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59
Factorial ANOVA:
Resloc: Pairwise Comparisons
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60
Factorial ANOVA:
Resloc: Univariate Tests
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61
Factorial ANOVA:
Interaction: Means, Std Errors, C.I.
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62
Factorial ANOVA:
Profile Plot: Gender*Resloc
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63
Factorial ANOVA:
Profile Plot: Resloc*Gender
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64
An Interactive Tutorial for
SPSS 10.0 for Windows©:
Factorial ANOVA
Click one of the following:
• Repeat this tutorial
• Return to the list of options in this tutorial
• Return to the list of tutorials
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65