Great work on the gretl software, it is extremely user-friendly compared to other econometrics programs. I have two questions I was hoping someone could answer. 1) if my model was something like the following: Mt = B1 + B2*Rt + B3*Yt + B4*Mt-1 + B5*Mt-2 + u - how would I perform a durbin wu hausman test for the hypothesis that my variable Rt is exogenous, if I use Rt-1 and Rt-2 as additional instruments - also, how would I estimate the above equation by generalized instrumental variables, treating Rt as endogenous, and Rt-1 and Rt-2 as additional instruments? 2) For a non-linear model such as: y = B1*x1 + B2*x2 + B3*x3^g + u -how can I use a succession of Gauss Newton Regressions to obtain the NLS estimates of all the parameters and their standard errors? Thank you so much for any help that can be provided. Regards, Rob