User Guide

538
Chapter 37
Assumptions. Observations should be independent, and errors should be uncorrelated
between items. Each pair of items should have a bivariate normal distribution. Scales
should be ad
ditive, so that each item is linearly related to the total score.
Related procedures. If you want to explore the dimensionality of your scale items (to
see if more than one construct is needed to account for the pattern of item scores), use
Factor Anal
ysis or Multidimensional Scaling. To identify homogeneous groups of
variables, you can use Hierarchical Cluster Analysis to cluster variables.
To Obtain a
Reliability Analysis
E From the m
enus choose:
Analyze
Scale
Reliability Analysis...
Figure 37-
1
Reliabili
ty Analysis dialog box
E Select two or more variables as potential components of an additive scale.
E Choose a model from the Model drop-down list.