Re: st: calculation of area under curve with stata

[Jorge Eduardo Pérez Pérez <jorge_perez@brown.edu>]

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 <elmir.omerovic@gmail.com> 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
>
>
>
> --
> View this message in context: http://statalist.1588530.n2.nabble.com/calculation-of-area-under-curve-with-stata-tp7580438.html
> Sent from the Statalist mailing list archive at Nabble.com.
> *
> *   For searches and help try:
> *   http://www.stata.com/help.cgi?search
> *   http://www.stata.com/support/faqs/resources/statalist-faq/
> *   http://www.ats.ucla.edu/stat/stata/

*
*   For searches and help try:
*   http://www.stata.com/help.cgi?search
*   http://www.stata.com/support/faqs/resources/statalist-faq/
*   http://www.ats.ucla.edu/stat/stata/