
From  Philipp Rehm <Philipp.Rehm@gmx.de> 
To  statalist@hsphsun2.harvard.edu 
Subject  Re: st: Simple programming question? 
Date  Tue, 17 Oct 2006 23:14:40 +0200 
Though I seem to be too simple to figure it out.
I have data like the following:
id day1 day2 day3 day4 day5 day6 ... day90
1 0 0 0 1 0 0 ... 0
2 0 0 0 0 1 1 ... .
3 1 1 1 1 1 1 ... 1
4 0 0 0 0 0 0 ... 0
Assume that a 1 on day`i' represents failure. I'm trying to generate a
variable that gives days to failure for survival analysis. E.g., subject 1
failed on day 4, subject 5 failed on day 5, subject 3 failed on day 1,
subject 4 did not fail and would be considered censored. 90 days worth of
data were collected but not all subjects were observed for the full 90day
period. Also note that subjects may be recorded as failing (drinking at
hazardous levels) on any combination of days during the 90day period. I'm
trying to calculate number of days to first failure. Seems like it should
be simple but I'm sufficiently naive that I've not solved it. Thanks.
Brad
Original Message
From: ownerstatalist@hsphsun2.harvard.edu
[mailto:ownerstatalist@hsphsun2.harvard.edu]On Behalf Of Nick Cox
Sent: Tuesday, October 17, 2006 1:16 PM
To: statalist@hsphsun2.harvard.edu
Subject: st: RE: Manipulating variables with repeated observations
You should find out about by:.
For example:
bysort MRN (VisitDate) : gen visit = _n by MRN : gen change = BMI[_N]  BMI[1]
Nick n.j.cox@durham.ac.uk
Karen R. Flórez
I have a dataset with kids BMIs that looks like this: MRN VisitDate BMI 123 10/20/04 30 123 6/11/05 25 123 4/14/06 25 222 222 222 Where MRN is the unique identifier. Kids had different visits at different times and BMI were take at each time. How can I generate a variable that codes for Visit 1,2,3,etc? So that I can measure the change between baseline and last followup?* * 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/ * * 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/
* * 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/
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