Modeling and Multivariate Methods - SAS

Chapter 12 Fitting Dispersion Effects with the Loglinear Variance Model 309
The Loglinear Report
Figure 12.4 Mean Model Output
Figure 12.5 Variance Model Output
The second portion of the report shows the fit of the variance model. The Variance Parameter Estimates
report shows the estimates and relevant statistics. Two hidden columns are provided:
• The hidden column exp(Estimate) is the exponential of the estimate. So, if the factors are coded to have
+1 and -1 values, then the +1 level for a factor would have the variance multiplied by the exp(Estimate)
value and the -1 level would have the variance multiplied by the reciprocal of this column. To see a
hidden column, right-click on the report and select the name of the column from the Columns menu
that appears.
• The hidden column labeled exp(2|Estimate|)is the ratio of the higher to the lower variance if the
regressor has the range -1 to +1.
The report also shows the standard error, chi-square, p-value, and profile likelihood confidence limits of
each estimate. The residual parameter is the overall estimate of the variance, given all other regressors are
zero.