Hello,
I am a new stata user, and I am trying to analyze the Willingness to Pay determinants and the payment levels. In order to do so I understand that I should stata. I think I have typed all the commands right but still a message : indipendent variable collinear with_cons shows up.
here is the command I have been using:
heckman wtpY1 age sex2 edu1 edu2 edu3 income Own2 Aware1, select (WTP1= age income sex2 edu1 edu2 edu3 ) twostep
wtpY1 stands for whether respondets are wlling to pay or not, while WTP1 stands for the level of payments given by those who are willing to pay.
the curious thing is that the command works well when the one of the indipendent variables is replaced with another variable. So I believe the collinearity arises because only those that are willing to pay give their payment level.
How can correct this problem, as I am on a tight deadline to submit my thesis.
Any help would be welcome
I am a new stata user, and I am trying to analyze the Willingness to Pay determinants and the payment levels. In order to do so I understand that I should stata. I think I have typed all the commands right but still a message : indipendent variable collinear with_cons shows up.
here is the command I have been using:
heckman wtpY1 age sex2 edu1 edu2 edu3 income Own2 Aware1, select (WTP1= age income sex2 edu1 edu2 edu3 ) twostep
wtpY1 stands for whether respondets are wlling to pay or not, while WTP1 stands for the level of payments given by those who are willing to pay.
the curious thing is that the command works well when the one of the indipendent variables is replaced with another variable. So I believe the collinearity arises because only those that are willing to pay give their payment level.
How can correct this problem, as I am on a tight deadline to submit my thesis.
Any help would be welcome
