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From | Nick Cox <njcoxstata@gmail.com> |
To | statalist@hsphsun2.harvard.edu |
Subject | Re: st: Multiple record per individual data: Counting frequency in which an individual changes from one variable value to another |
Date | Sat, 6 Aug 2011 09:21:54 +0100 |
bysort study_id : gen different = sum(X != X[_n-1]) & _n > 1) by study_id : replace different = different[_N] See -tsspell- from SSC and SJ-7-2 dm0029 . . . . . . . . . . . . . . Speaking Stata: Identifying spells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . N. J. Cox Q2/07 SJ 7(2):249--265 (no commands) shows how to handle spells with complete control over spell specification Nick On Fri, Aug 5, 2011 at 10:04 PM, Weichle, Thomas <Thomas.Weichle@va.gov> wrote: > I have data which contains multiple records per individual. I have a > categorical variable X (values 1,2,3) which can vary from record to > record within the individual. I'd like to know if there is a command > that will count the number of times in which an individual changes to a > different value in variable X. Consider the following example: > > study_id X > 100 2 > 100 2 > 100 2 > 100 3 > 555 1 > 555 1 > 555 2 > 555 2 > 555 1 > 555 1 > > study_id 100 would count as 1 change. > study_id 555 would count as 2 changes. * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/