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Re: st: calculation of area under curve with stata
From
Jorge Eduardo Pérez Pérez <[email protected]>
To
"[email protected]" <[email protected]>
Subject
Re: st: calculation of area under curve with stata
Date
Wed, 16 Oct 2013 14:56:42 -0400
I am not sure if I am understanding this correctly, but I think you
want to calculate the area under the curve of a plot of BP measures
against time for each animal. This could be achieved by calculating
the area under each trapezoid for each measure and adding them:
clear
set seed 1234
set obs 10
gen time=_n+uniform()
gen measure=uniform()
twoway area measure time
* Area of trapezoid for each time
gen area=(measure+measure[_n-1])*(time-time[_n-1])*0.5
* Add them
egen tarea=total(area)
sum tarea
Hope this helps,
--------------------------------------------
Jorge Eduardo Pérez Pérez
Graduate Student
Department of Economics
Brown University
On Mon, Oct 14, 2013 at 4:38 AM, elmir <[email protected]> wrote:
> Dear All,
>
> I am analyzing the blood pressure (BP) levels from the three different
> groups of animals. BP was measured repeatedly in every animal at 10
> different time points within 90 minutes from the start of the experiment.
> The animals were exposed to 3 different drugs (each group n=8).
>
> I understand that one way to compare the effect of the drugs on blood
> pressure within the whole experimental period would be to calculate the area
> under the curve and to use this value in a linear mixed model.
>
> I would be very grateful if someone could help me with step-by-step
> instructions how to calculate AUC in stata.
>
> Kind regards
>
> Elmir Omerovic MD, PhD
> Sahlgrenska University Hospital
> Gothenburg, Sweden
>
>
>
> --
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