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Chapter 21
Those who drive less frequently show greater support for the bill than those who drive more
frequently.
The coefficients for the variables gender and votelast, in addition to not being statistically
significant, appear to be small compared to other coefficients.
The design effects indicate that some of the standard errors computed for these parameter
estimates are larger than those you would obtain if you used a simple random sample, while
others are smaller. It is vitally important to incorporate the sampling design information in your
analysis because you might otherwise infer, for example, that the coefficient for the third level
of Age category, [agecat=3],issignificantly different from 0!
Classification
Figure 21-9
Categorical variable information
Given the observed data, the “null” model (that is, one without predictors) would classify all
customers i nto the modal group, Agree. Thus, the null model would be correct 27.3% of the time.
