There are at least two ways to do that; the first is the menu-only way, which can become a bit tedious if you actually want to look at all the results:

- again, "dummify" the AreaRegion variable - right-click, choose dummify

- go to Sample / Restrict by condition, and choose the first created dummy (DAreaRegion_1) to sub-sample the data

- right-click the population variable, choose Basic statistics; you get a new result window with the mean value at the top of the list

- the right-most button in that new window is for choosing the number of significant digits

So in that sense it's actually not entirely true that gretl only gives you five significant digits for the summary (contrary to what I thought as well). If you want to look at all ten results, you would have to repeat the steps above for the other dummies as well.

Or you do a tiny bit of scripting in the console, by assigning the result from the aggregate() function call (applied to the full sample) to a matrix:

matrix m = aggregate(population, AreaRegion, mean)

Then you can look at the created object m by opening the "icon view" (menu View/Icon view). Double click on the icon for "m". The third column in the new window holds your results. By going to View/Format in that window you can change the format setting to other numbers of significant digits there.

cheers

sven