One-way MANOVA using SPSS

Introduction

The one-way MANOVA is used to determine whether there are any differences between independent groups on more than one continuous dependent variable. In this regard, it differs from a one-way ANOVA only in measuring more than one dependent variable at the same time, unlike the one-way ANOVA that only measures one dependent variable.

Assumptions

One independent variable consists of two or more categorical independent groups.
Two or more dependent variables that are either interval or ratio (continuous) (see our guide on Types of Variable).
Multivariate Normality
Equality of variances between the independent groups (homogeneity of variances).
Independence of cases.

Example

A high school takes its intake from three different primary schools. A teacher was concerned that, even after a few years, there were academic differences between the pupils from the different schools. As such, she randomly selected 20 pupils from School A, 20 pupils from School B and 20 pupils from School C and measured their academic performance as assessed by the marks they received for their end-of-year English and Maths exams.

Setup in SPSS

The independent variable separating boys and girls has been labelled "Gender" with "Male" and "Female" categories. The dependent variables, English and Maths exam mark, were labelled "English_Score" and "Maths_Score", respectively. To know how to correctly enter your data into SPSS in order to run a one-way MANOVA please read our Entering Data in SPSS tutorial.

Test Procedure in SPSS

Click Analyze > General Linear Model > Mulivariate... on the top menu as shown below:

Published with written permission from SPSS Inc, an IBM Company.
You will be presented with the Multivariate dialogue box:

Published with written permission from SPSS Inc, an IBM Company.
Transfer the independent variable, "School", into the "Fixed Factor(s):" box and transfer the dependent variables, "English_Score" and "Maths_Score", into the "Dependent Variables:" box. You can do this by drag-and-dropping the variables into their respective boxes or by using the button. For older versions of SPSS, you will need to use the latter method. The result is shown below: button. If you are using older versions of SPSS you will need to use the former method. The result is shown below:
[For this analysis, you will not need to use the "Covariate(s):" (used for MANCOVA) or "WLS Weight:" boxes.]

Published with written permission from SPSS Inc, an IBM Company.
Click on the button. You will be presented with the Multivariate: Profile Plots dialogue box:

Published with written permission from SPSS Inc, an IBM Company.
Transfer the independent variable, "School", into the "Horizontal Axis:" box, as shown below:

Published with written permission from SPSS Inc, an IBM Company.
Click the button. You will see that "School" has been added to the "Plots:" box, as shown below:

Published with written permission from SPSS Inc, an IBM Company.

Click the button. This will return you to the Multivariate dialogue box.
Click the button. You will be presented with the Multivariate: Post Hoc Multiple Comparisons for Observed... dialogue box, as shown below:

Published with written permission from SPSS Inc, an IBM Company.
Transfer the independent variable, "School", into the "Post Hoc Tests for:" box and select the "Tukey" checkbox in the "Equal Variances Assumed" area, as shown below:
[You can select other post-hoc tests depending on your data and study design. If your independent variable only has two levels/categories, you do not need to complete this post-hoc section.]

Published with written permission from SPSS Inc, an IBM Company.
Click the button. This will return you to the Multivariate dialogue box.
Click the button. This will present you with the Multivariate: Options dialogue box, as shown below:

Published with written permission from SPSS Inc, an IBM Company.
Transfer the independent variable, "School", from the "Factor(s) and Factor Interactions:" box into the "Display Means for:" box. Select the "Descriptive statistics", "Estimates of effect size", "Observed power" and "Homogeneity tests" checkboxes in the "Display" area. You will be presented with the following screen:

Published with written permission from SPSS Inc, an IBM Company.
Click the button. This will return you to the Multivariate dialogue box.
Click the button to generate the output.