ESTIMATE
’label’ contrast-specification <(divisor=n)>
<, ’label’ contrast-specification <(divisor=n)>> <, …> </ options>;
The ESTIMATE statement provides a mechanism for obtaining custom hypothesis tests. As in the CONTRAST statement, the basic element of the ESTIMATE statement is the contrast-specification, which consists of MODEL and RANDOM effects and their coefficients. Specifically, a contrast-specification takes the form
< fixed-effect values …> < | random-effect values …>
Based on the contrast-specifications in your ESTIMATE statement, PROC HPMIXED constructs the matrix , as in the CONTRAST statement, where is associated with the fixed effects and is associated with the G-side random effects.
PROC HPMIXED then produces for each row of an approximate t test of the hypothesis , where . Results from all ESTIMATE statement are combined in the "Estimates" ODS table.
Note that multi-row estimates are permitted. Unlike the CONTRAST statement, you need to specify a ’label’ for every row of the multi-row estimate, since PROC HPMIXED produces one test per row.
PROC HPMIXED selects the degrees of freedom to match those displayed in the "Type III Tests of Fixed Effects" table for the final effect you list in the ESTIMATE statement. You can modify the degrees of freedom by using the DF= option. If you select DDFM= NONE and do not modify the degrees of freedom by using the DF= option, PROC HPMIXED uses infinite degrees of freedom, essentially computing approximate z tests.
If PROC HPMIXED finds the fixed-effects portion of the specified estimate to be nonestimable, then it displays "Non-est" for the estimate entry.
The construction of the matrix for an ESTIMATE statement follows the same rules as listed under the CONTRAST statement.
Table 49.5 summarizes the options available in the ESTIMATE statement.
Table 49.5: ESTIMATE Statement Options
Option |
Description |
---|---|
Specifies the confidence level |
|
Constructs t-type confidence limits |
|
Specifies the degrees of freedom |
|
Specifies values to divide the coefficients |
|
Displays the matrix coefficients |
|
Sets up random-effect contrasts between groups |
|
Tunes the estimability checking |
|
Sets up random-effect estimates between subjects |
You can specify the following options in the ESTIMATE statement after a slash (/).