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st: Re: Area Under Curve


From   "Sergiy Radyakin" <Radyakin@aoek.uni-hannover.de>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: Re: Area Under Curve
Date   Fri, 2 Mar 2007 17:14:27 +0100

Hello Paola,

here is an example:
http://www.boomer.org/c/p3/c02/c0210.html

refer to the formula AUC(1-n)

*** Since you need only the area under the curve, but above 180, transform your data first:
replace c=(c-180)*(c>180)
*** c is your concentration variable
*** Since t(n)-t(n-1) is always 5 minutes, so you can simplify the calculations.
gen y=c
replace y=c[_n]+y[_n-1] if _n>1
di y[_N]/2*5


This will yield mg.min/L. If you want mg.hr/L, replace 5 in the last expression with 5/60, etc


Regards, Sergiy



----- Original Message ----- From: "Di Stefano, Paola" <paola.di.stefano@medtronic.com>
To: <statalist@hsphsun2.harvard.edu>
Sent: Friday, March 02, 2007 4:46 PM
Subject: st: Area Under Curve



Dear all,
Does anybody know how to calculate the Area Under Curve?
I have two variables: time from 00.00 a.m. to 23.55 p.m. and glicemic
values from 40 mg to 350 mg (every 5 minutes).
I would like to estimate tha area above a limit of 180 mg.
Any suggestion is welcome!
Paola

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