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Two observations up front:
You do not have to use -:mylabel, auto- here. I used it a while back
to -input- a string that should have labels attached automatically, but your
vars are numeric.
In your -forv- you replace the variable "count" which does not exist. You
also want to make "Id" lowercase for your code to stand a chance...
HTH
Martin
_______________________
----- Original Message -----
From: <[email protected]>
To: <[email protected]>
Sent: Sunday, May 31, 2009 3:07 PM
Subject: st: Count occurrence and duration of states in panel data
I want to know how often a person has been in a certain state (e.g. state
2) during the past 30 days before the current state. Important is that the
current state should not count.
I have data in which the time intervals are not of equal length. And to
keep things for the moment simple I defined a variable s2 which takes on
the value 1 if the state of interest occurs. The variable res shows my
desired results.
clear
input id begin end state s2 res :mylabel , auto
1 12 14 1 . 0
1 15 46 2 1 0
1 47 52 3 . 1
1 59 66 2 1 1
1 70 80 1 . 1
1 81 88 2 1 1
1 89 105 1 . 2
2 14 21 2 1 0
2 55 59 3 . 1
2 61 109 1 . 0
2 110 115 2 1 0
2 116 200 1 . 1
end
I followed some earlier questions at statalist and stata tips 39, 51 on
inrange and events in intervals:
gen count = .
local N = _N
qui forval i = 1/`N' {
egen tag = tag(s2) ///
if Id == Id[`i'] & ///
inrange(begin, begin[`i'] - 30, end)
count if tag == 1
replace count = r(N) in `i'
drop tag
}
l, sepby(Id)
I surmise that the inrange command is not appropriate. As s2 should also
count if even the begin date has been more than 30 days away but the
person is in the state within the 30 day interval (with respect to the end
date),
Can inrange be adjusted such that it takes the begin date and the end date
into account? Do I have to think about an entirely different approach?
The next step would be to calculate the duration the person has been in s2
during the past 30 days. If there is a related solution I would be
extremely happy if you let me know this as well.
Any ideas will be appreciated!
Elke
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