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Re: st: identify group of observations


From   Doug Owens <dho@tamu.edu>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: identify group of observations
Date   Wed, 28 Apr 2004 21:47:13 -0500

At 08:54 PM 4/28/2004 -0500, you wrote:
At 06:08 PM 4/28/2004 -0400, MITRA PINAKI  (MAR1PXM) wrote:
Hello List,

I have a data set where I need to group observations. The identifying flag
is two character string which can be either "01" or "02". Each "01"
observation is followed by "02", so the flag for the first obs is "01" and
the very next one's is "02". But these are always not in pair; order can be
"01" and "02"; "01", "02", "02"; "01", "02", "02, "02" and so on. All the
"02" obs. followed by "01" belong to one group. Is there any way I can
generate an identifier that indicates these groups?

Do you have that backwards? i.e. All the "01" obs. followed by "02" belong to one group. That would have been my guess based on your examples.
Assuming you want to create grp like:
Flag  grp
01      1
02      1
01      2
02      2
02      2
01      3
02      3
02      3
02      3

Then you can just
gen grp = flag=="01"
replace grp = sum(grp)















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