bys id (observation) : gen zero = Activity == 0
bys id zero (observation) : gen nzero = _N if zero == 0
replace nzero = 0 if nzero == .
gen activity2 = activity if nzero < 60 & nzero
-- Maarten
--- BW Wheeler <[email protected]> wrote:
> Dear all,
>
> I'm having trouble figuring out a solution to this data management
> problem,
> and have exhausted all books and findit (partly as it's hard to know
> what
> to search for)!
>
> I have time series data captured from accelerometers, with an
> observation
> of 'activity counts' logged every 10 seconds for several days for
> each
> individual. If the number of counts is zero continuously for any
> period of
> 10 minutes or more (i.e. 60+ observations), we need to assume that
> the
> accelerometer was not being worn, and to treat these zeros as
> missing.
>
> So, my data look something like this:
>
> Observation Date Time Activity
> 1 13/05/2006 15:20:00 230
> 2 13/05/2006 15:20:10 215
> 3 13/05/2006 15:20:20 0
> 4 13/05/2006 15:20:30 0
> 5 13/05/2006 15:20:40 0
> ...
>
> Does anyone have any ideas of how I can replace the 'Activity' value
> with
> missing, if that value is a zero in the midst of a continuous series
> of 60+
> zeros?
>
> Any advice very gratefully received
> Thanks,
> Ben
>
> ----------------------
> Ben Wheeler
> Research Fellow
> Department of Social Medicine, University of Bristol
> & South West Public Health Observatory
> [email protected]
>
> *
> * For searches and help try:
> * http://www.stata.com/support/faqs/res/findit.html
> * http://www.stata.com/support/statalist/faq
> * http://www.ats.ucla.edu/stat/stata/
>
-----------------------------------------
Maarten L. Buis
Department of Social Research Methodology
Vrije Universiteit Amsterdam
Boelelaan 1081
1081 HV Amsterdam
The Netherlands
visiting address:
Buitenveldertselaan 3 (Metropolitan), room Z434
+31 20 5986715
http://home.fsw.vu.nl/m.buis/
-----------------------------------------
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