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Simple constraint on logistic regression?
Posted: Thu Sep 11, 2014 2:36 pm
by AmberA
Hi,
I wanted to run the logistic regression
Logit k x y z
Under the constraint c1+c2+c3=1 where c1,c2,c3 are the coefficients on x,y,z. This seems easy to do for least squares but I can’t see a way to do it for logit. Any help would be greatly appreciated.
Thanks!
Amber
Re: Simple constraint on logistic regression?
Posted: Thu Sep 11, 2014 2:58 pm
by EViews Gareth
Same as with Least Squares:
Re: Simple constraint on logistic regression?
Posted: Thu Sep 11, 2014 3:17 pm
by AmberA
That worked! Thanks!
Is there a way to figure out the Standard Error for the constrained variable (c(3) in this case)?
Amber
Re: Simple constraint on logistic regression?
Posted: Thu Sep 11, 2014 4:36 pm
by startz
sqrt(var(c(1))+var(c(2))+2cov(c(1),c(2))) I think.
Re: Simple constraint on logistic regression?
Posted: Thu Sep 11, 2014 5:04 pm
by AmberA
Yes, thanks, but where do you find the covariance matrix in the output?
It appears that another way to get the standard error is to run the regression several times while putting the constrained coefficient (1-c(1)-c(2)) on a different explanatory variable each time.
Thanks again!
Amber
Re: Simple constraint on logistic regression?
Posted: Thu Sep 11, 2014 5:06 pm
by startz
View/Covariance matrix
Re: Simple constraint on logistic regression?
Posted: Thu Sep 11, 2014 5:09 pm
by AmberA
Thanks!