st: Identifying the second occurrence of event in panel data

[Daniel Sage <daniel.sage@stir.ac.uk>]

Hello,

I have panel data and wish to record the second occurrence of an event.  The event is unemployment.  So for example I want to do the following:

ID YEAR UNEMPLOYED FIRST SECOND
1 1 0 0 0
1 2 1 1 0
1 3 1 0 0
1 4 0 0 0
1 5 0 0 0
1 6 0 0 0
1 7 1 0 1
1 8 1 0 0
1 9 1 0 0
1 10	1 0 0

I am able to identify the first occurrence of unemployment using the following:

by pid (wav), sort: gen noccur = sum(unemployed)
by pid: gen byte first = noccur == 1 & noccur[_n-1] != noccur

But I am unsure how to identify the second occurrence.  Any help and explanations very welcome.

Daniel
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