On Fri, 18 Jun 2021, George Matysiak wrote: I'm not sure I understand what you mean, but I'll give it a shot anyway: if you want to create a dummy variable holding included/excluded observations, there is more than one way to do so: a particularly simple one is to create a series of 1s when subsampling is in effect and then fill the excluded observation with 0s, as in <hansl> open data7-24 smpl 100 --random series selected = 1 ols salepric const sqft age city smpl full selected = misszero(selected) </hansl> of course, more sophisticated variants of the above are possible. ------------------------------------------------------- Riccardo (Jack) Lucchetti Dipartimento di Scienze Economiche e Sociali (DiSES) Università Politecnica delle Marche (formerly known as Università di Ancona) r.lucchetti(a)univpm.it http://www2.econ.univpm.it/servizi/hpp/lucchetti -------------------------------------------------------