Gretl is perceived by some people as a primarily time-series oriented package. Although this is true to some extent (IMO we need to work in that direction, in the long run), you can do some basic microeconometrics with gretl, especially via the newly introduced features that will show up in 1.5.1. Attached you will find a zip file which shows you how to estimate a linear model with endogenous sample selection by using Heckman's two-step estimator (the so-called "Heckit" estimator). I thought I'd share it with you guys also because it makes for a nice showcase of the new features, especially matrices. In the zip file you will find 3 files: heckit.inp - contains the actual "heckit" function greene22_7.inp - replicates the example from W. Greene's textbook mroz.gdt - data for the above example Note that you'll need the CVS version for running this, until 1.5.1 is released. Comments are welcome. -- Riccardo "Jack" Lucchetti Dipartimento di Economia Facoltà di Economia "G. Fuà" Ancona