Dear Bruno,

 

It seems that you are running a regresion with boht logarea and yhat1, however, gretl drops one of the variable because they collinear. That is right given that correlation is 99.93%

 

      abertura     logrendpc       logarea         yhat1
        1.0000        0.1402       -0.6693        0.6698  abertura
                      1.0000       -0.1715        0.2093  logrendpc
                                    1.0000       -0.9993  logarea
                                                  1.0000  yhat1

Now, your question is why you have a different dropped variable if you change the order of the regressors, right? I am not sure why that is the case, but it happens also in other packages. I remember similar issue in Stata, when you have a different dropped variable if you use a different command, but forcing to apply the same procedure. For example comparing OLS con IV (but with trivial instruments).

 

Although, I don't have the question I think is not a serious problem. If 2 variables are highly correlated then any of those can be used. Indeed, many times you could cut down your regressor into principal components to avoid collinearity. Moreover, yhat1 is predicted variable from a previous model and it is likely that logarea (or some similar variable) is a relevant in that model.

 

Best, Rodrigo.