CONTRAST 'label' expression <, expression> <option>;
The CONTRAST statement enables you to conduct a statistical test that several expressions simultaneously equal zero. The expressions are typically contrasts—that is, differences whose expected values equal zero under the hypothesis of interest.
In the CONTRAST statement, you must provide a quoted string to identify the contrast and then a list of valid SAS expressions separated by commas. Multiple CONTRAST statements are permitted, and results from all statements are listed in a common table. PROC NLIN constructs approximate F tests for each statement by using the delta method (Cox 1998) to approximate the variance-covariance matrix of the constituent expressions.
You can specify the following option: