User Guide

18
Chapter 2
Univariate or GLM Multivariate. If there are only two measurements for each subject
(for example, pre-test and post-test), and there are no between-subjects factors, you can
use the Paired-Samples T Test procedure.
GLM Repeated Measures Define Factor(s)
GLM Repeated Measures analyzes groups of related dependent variables that represent
different measurements of the same attribute. This dialog box lets you define one or
more within-subjects factors for use in GLM Repeated Measures. Note that the order
in which you specify within-subjects factors is important. Each factor constitutes a
level within the previous factor.
To use Repeated Measures, you must set up your data correctly. You must define
within-subjects factors in this dialog box. Notice that these factors are not existing
variables in your data but rather factors that you define here.
Example. In a weight-loss study, suppose the weights of several people are measured
each week for five weeks. In the data file, each person is a subject or case. The
weights for the weeks are recorded in the variables weight1, weight2, and so on. The
gender of each person is recorded in another variable. The weights, measured for
each subject repeatedly, can be grouped by defining a within-subjects factor. The
factor could be called week, defined to have five levels. In the main dialog box, the
variables weight1, ..., weight5 are used to assign the five levels of week. The variable
in the data file that groups males and females (gender) can be specified as a between-
subjects factor to study the differences between males and females.
Measures. If subjects were tested on more than one measure at each time, click
Measure to define the measures. For example, the pulse and respiration rate could be
measured on each subject every day for a week. These measures do not exist as
variables in the data file but are defined here. A model with more than one measure is
sometimes called a doubly multivariate repeated measures model.
To Obtain a GLM Repeated Measures Analysis
 From the menus choose:
Analyze
General Linear Model
Repeated Measures...