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The AUTOREG Procedure |
The AUTOREG procedure now supports a RESTRICT statement for constrained estimation.
Each restriction is written as a linear equation composed of constants and parameter names. Refer to model parameters by the name of the corresponding regressor variable. Each name used in the equation must be a regressor in the preceding MODEL statement. Use the keyword INTERCEPT to refer to the intercept parameter in the model.
The following is an example of a RESTRICT statement:
model y = a b c d; restrict a+b=0, 2*d-c=0;
When restricting a linear combination of parameters to be 0, you can omit the equal sign. For example, the following RESTRICT statement is equivalent to the preceding example:
restrict a+b, 2*d-c;
The following RESTRICT statement constrains the parameters estimates for three regressors (X1, X2, and X3) to be equal:
restrict x1 = x2, x2 = x3;
The preceding restriction can be abbreviated as follows.
restrict x1 = x2 = x3;
Only simple linear combinations of parameters can be specified in RESTRICT statement expressions; complex expressions involving parentheses, division, functions, or complex products are not allowed.
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