Regression with interval for estimate

[jebuske]

Hi,

This is the regression model i'm using:

proc reg data=data_regressie4 outest=regressie4 edf;
BY ANALYS;
model geschaalde_FE = geschaalde_deviation age size total_experience firm_experience aantalsector aantalbedrijf;
run;

The problem is that the estimate for geschaalde_deviation should be greater than 0. Is there a way to make sas estimate this model with "geschaalde_deviation" being greater than 0?

Thanks a lot!

[Paige]

There is a RESTRICT statement in PROC REG, but it doesn't allow "greater than" restrictions, just equality restrictions.

The problem isn't really SAS. The problem is that when you perform a regression with multiple correlated variables (you have 7 variables in your model), least squares regression (not SAS) can have huge variances for your parameter estimates, and because of that, you can get a negative estimate even when you think it should be positive. In this situation, interpreting the coefficients is a meaningless exercise.

Sometimes using Partial Least Squares regression (PROC PLS) can alleviate this problem, but your R-squared from PLS will not be as good as from PROC REG, and there's no guarantee that PLS will provide positive estimates.