Allin, thank you very much. It functions perfectly. Dolores. -----Mensagem original----- De: Allin Cottrell [mailto:cottrell@wfu.edu] Enviada em: sábado, 5 de março de 2011 17:33 Para: madmdiaz(a)usp.br; Gretl list Assunto: Re: [Gretl-users] intreg doubt On Sat, 5 Mar 2011, Maria Dolores Montoya Diaz wrote: This doesn't sound like a case for interval regression. But you can easily get tobit to do the job; just transform Y so it's censored at 0 instead of at 1000. series TY = 1000 - Y TY = (TY < 0)? 0 : TY series TX = -X tobit TY 0 TX The coefficient reported for TX is the same as that reported by Stata for tobit ycens x, ul(1000). There's no built-in equivalent to "truncreg", no. Allin Cottrell