You might try -pkexamine-, Stata's built-in program
for such data.
Tom
> -----Original Message-----
> From: [email protected] [mailto:[email protected]]
> Sent: Tuesday, September 24, 2002 2:05 PM
> To: [email protected]
> Subject: st: Area under the curve trouble with aucdist
>
>
>
> I need to calculate the area under the curve (viral load over
> time) for
> about 1000 study participants using the trapezoidal rule. I have used
> aucdist but I am not getting a result and am not sure if I'm
> getting an
> error message.
>
> id = patient id
> time = time of viral load test
> conc = viral load value
>
> aucdist id time conc, t generate(auc)
>
> (t specifies that the integral be computed using the simple
> trapezoidal
> rule, and generate(auc) specifies to create a new variable
> with the AUC (C
> max, T max, log conc 0 -inf.))
>
> but all I'm getting is (2000) in return which is supposed to
> mean that I
> have no observations on which to perform the statistical operation.
>
> I have 9500 observations with multiple observations per
> patient, there are
> no missing data. Any suggestions as to what I may be doing wrong?
> *
> * 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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