[R] Find a particular point on a curve

[David Winsemius]

On Oct 7, 2011, at 11:54 AM, Joanie wrote:

> Hi,
> my question is really precise.
>
> I'm interested in drops of stomacal temperature (of seal pups)  
> following
> milk ingestion. Temperature starts at an average of 37.8oC (sd=0.2)  
> and
> drops rapidly to around 36.0oC and then stabilizes slowly to a  
> temperature
> silimar to the previous one. It looks a bit like an inverse skewed  
> bell
> curve.
>
> I want to find different points on that curve, and I have a hard  
> time trying
> to code one of them.
>
> I want to determine the point after ingestion (after the temperature  
> drop)
> where the temperatures reaches stability, i.e. where temperature is  
> stable
> to plus or minus 1 sd for a period of 10 minutes or more. I have  
> data almost
> every second and I calculated that a 10 minutes period corresponded  
> to an
> average of 400 lines.

You would get much better advice if you posted a sample. 400 data  
points is not very big.
>
> Also, I want to determine the area under the curve, i.e. the area  
> enclosed
> by the inverse skewed curve (which I don't know the equation).

Wouldn't that just be:

  sum(vec-vec[1])

-- 

David Winsemius, MD
West Hartford, CT