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Re: st: complex panel data variable generation question


From   Nick Cox <njcoxstata@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: complex panel data variable generation question
Date   Thu, 1 Sep 2011 18:33:29 +0100

It sounds as if you need to get your observations into the right order.

bysort i epoch (t) : gen last = _n == _N
bysort i (last t) : gen diff = x - x[_n-1] if last

On Thu, Sep 1, 2011 at 5:28 PM, Hoffman, George <ghoffman@mcw.edu> wrote:
> I have a panel dataset of observations in individuals (i=1-15) over time (t=1-4000)
> The observations are sequential by minute, but the duration of observation for each individual is not identical.
> I have xtdes, i(i) t(t)
>
> Within the observation period are epochs (1-8) defined by events that do not occur at identical intervals but do occur sequentially.
> In additional to the observations that occur at minute intervals are measurements made only at the end of each epoch.
>
> What I would like to do is generate a difference between the measures made once per epoch, but since these observations do not occur at regular intervals I can't get his to work (using sorting, by i: gen...)
>
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