<>
The basis for all out acrobatic maneuvers with your seemingly simple problem is -as always- Nick`s http://www.stata-journal.com/sjpdf.html?articlenum=pr0004
HTH
Martin
-----Ursprüngliche Nachricht-----
Von: [email protected] [mailto:[email protected]] Im Auftrag von Martin Weiss
Gesendet: Montag, 5. Oktober 2009 17:11
An: [email protected]
Betreff: st: AW: AW: Keep subsequent observations in panel data
<>
The second one could be as easy (LOL) as
*************
clear*
inp byte(i t y)
1 1 0
1 2 0
1 5 0
1 6 0
1 7 0
1 8 0
2 2 0
2 5 0
2 6 0
2 7 0
2 8 0
end
compress
bys i: keep if /*
*/ sum((t-t[_n-1])>1)<=1
*************
although you want to check this carefully...
HTH
Martin
-----Ursprüngliche Nachricht-----
Von: [email protected] [mailto:[email protected]] Im Auftrag von Martin Weiss
Gesendet: Montag, 5. Oktober 2009 16:58
An: [email protected]
Betreff: st: AW: Keep subsequent observations in panel data
<>
The first case should be as easy as
*************
clear*
inp byte(i) t y
1 1 0
1 2 0
1 5 0
1 6 0
1 7 0
1 8 0
2 2 0
2 5 0
2 6 0
2 7 0
2 8 0
end
compress
bys i:gen spell=_n
keep if t==spell
l, noobs sepby(i)
*************
HTH
Martin
-----Ursprüngliche Nachricht-----
Von: [email protected] [mailto:[email protected]] Im Auftrag von Nikolaos Kanellopoulos
Gesendet: Montag, 5. Oktober 2009 16:28
An: [email protected]
Betreff: st: Keep subsequent observations in panel data
Dear all,
I have a very simple unbalanced panel, where individuals are allowed to drop in and out of the sample. I want to create two separate datasets with the following sampling criteria.
For the first one, individuals that appear in the first wave should remain in the sample at subsequent years until the first time they drop out of the panel,
either completely or not. If they rejoin the panel later these observations should not be used. For instance in the following example I want to keep only observations 129 and 130.
+----------------------+
i t y
----------------------
129. 1 1 0
130. 1 2 0
133. 1 5 0
134. 1 6 0
135. 1 7 0
136. 1 8 0
+----------------------+
137. 2 2 0
138. 2 5 0
139. 2 6 0
140. 2 7 0
141. 2 8 0
+----------------------+
For the second dataset individuals should remain in the sample at subsequent years from the first time they are observed until the first time they drop out of the panel, either completely or return again. Again , if they rejoin the panel later these observations should not be used. For instance in the following example I want to keep only observations 129 to 130 and 137.
+----------------------+
i t y
----------------------
129. 1 1 0
130. 1 2 0
133. 1 5 0
134. 1 6 0
135. 1 7 0
136. 1 8 0
+----------------------+
137. 2 2 0
138. 2 5 0
139. 2 6 0
140. 2 7 0
141. 2 8 0
+----------------------+
Thanks
Nikos
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