On Thu, 10 Mar 2011, Austin Spry wrote: Hello Austin, I don't suppose you are doing aything brainless, but I don't know exactly what your dataset looks like, and on the face of it what you are reporting is puzzling. When you restrict the sample, starting from a panel dataset, gretl checks to see if the restricted sample can still be interpreted as a panel, and it drops back to a cross-sectional interpretation only if the panel interpretation seems to be unavailable. Obviously, a panel interpretation makes sense only if the restricted sample still contains at least two groups and at least two time periods. By way of illustration, consider this gretl script (greene14_1 is a panel dataset comprising 6 "units" or "groups" observed over 15 time periods): open greene14_1.gdt series foo = (unit==1 || unit==3)? 1 : 2 The "foo" series is intended to emulate your "Stand" variable. If you now restrict the sample using "foo = 1" as criterion, you get a panel with two groups, corresponding to the original "units" 1 and 3. If you restore the full sample then subsample using "foo = 2" as the criterion, you again get a panel, comprising the original "units" 2, 4, 5 and 6. If you're using a very old version of gretl this might not work as described. The current version is 1.9.4. Allin Cottrell