# Multiple Regression under constraints

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Xavier on 8 Feb 2012
Answered: Sophy on 1 Nov 2018
Hi,
I am looking at doing a linear multiple regression on one dependent variable and 15 independent varaibles. My first issue is that I would like to be sure there is no multicollinearity in between the IV. Is there a function to take care of that? I guess some forward, backward, stepwise could partially take care of that. My second issue is that I would like to have constraints on the beta coefficient. For example I would like beta1>0.5 and beta2<1... Would you have any suggestion regarding the function to use.

Richard Willey on 8 Feb 2012
Given that you want to place constraints on your coefficients, you're going to need to use Optimzation Toolbox. The constraints that you're describing a pretty simple, so you should be able to use lsqcurvefit.
Let's move onto the multicollinearity question:
I'd start by using something simple like a scatterplot matrix to visualize the data, and follow up by calculating some simple summary statistics.
If you determine that multicollinearity is a problem, your best best will be to wrap the sequentialfs function from Statistics Toolbox around lsqcurvefit.

Sophy on 1 Nov 2018
Hi Guys, I would like to use Linear regression with constraints on equality of some of features' coefficients. Anyone know how to define this? For example I have 6 features and features No 1 and 5 need to have equal coefficients also features 2 and 4 should have the same coefficients in the linear regression model. I really appreciate if anyone can help me. Thanks,