--- carmen gamarra <[email protected]> wrote:
> I know how I would like to cancel a selection and continue working
> with all the variables or category of a variable?
>
> Example: keep if yearfile=="1996"
>
> and then (cancel select) cancel the selection and working with all
> the categories:
-keep if expression- means you throw away everything for which
expression is false. Once you throw it away, it is gone forever (unless
you follow strategy 1 below).
There are two strategies you can follow:
1)
preserve
keep if yearfile == "1996"
reg y x /// regression on selection
restore
reg y x /// regression on complete file
2)
gen byte touse96 = yearfile == "1996"
reg y x if touse96 /// regression on selection
reg y x /// regression on complete file
see -help preserve- for more on strategy 1, and -help if- for more on
strategy 2. In most cases I would prefer strategy 2.
Hope this helps,
Maarten
-----------------------------------------
Maarten L. Buis
Department of Social Research Methodology
Vrije Universiteit Amsterdam
Boelelaan 1081
1081 HV Amsterdam
The Netherlands
visiting address:
Buitenveldertselaan 3 (Metropolitan), room Z434
+31 20 5986715
http://home.fsw.vu.nl/m.buis/
-----------------------------------------
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