# RE: st: finding a peak in an asymmetric curve

 From "Maarten Buis" <[email protected]> To <[email protected]> Subject RE: st: finding a peak in an asymmetric curve Date Tue, 11 Apr 2006 12:30:20 +0200

```Ah, Ron�n's interpretation of your question makes a lot more sense.

-----------------------------------------
Maarten L. Buis
Department of Social Research Methodology
Vrije Universiteit Amsterdam
Boelelaan 1081
1081 HV Amsterdam
The Netherlands

Buitenveldertselaan 3 (Metropolitan), room Z214

+31 20 5986715

http://home.fsw.vu.nl/m.buis/
-----------------------------------------

-----Original Message-----
From: [email protected] [mailto:[email protected]]On Behalf Of Ron�n Conroy
Sent: dinsdag 11 april 2006 12:24
To: [email protected]
Subject: Re: st: finding a peak in an asymmetric curve

On 11 Aib 2006, at 09:17, Yoshiro Nagao wrote:

> Are there any statistical method
> to find the value of x for the peak,
> and show its "significance"?

Check Stata's routines for analysis of pharmacokinetic data (pretend
your nutrient values are time and you'll fool it).

. pkexamine nutrient longevity

Warning: the point (0, 0) is not in your data.  It will be added.

Maximum concentration =
362.5851
Time of maximum concentration
=       .02
Time of last observation (Tmax) =   .
049458
Elimination rate =
15.2374
Half life =
0.0455

Area under the curve

-----------------------------------------------------------------------
|    AUC [0, inf.)    | AUC [0, inf.) |  AUC [0,
inf.)
AUC [0, Tmax]  | Linear of log conc. |   Linear fit  |
Exponential fit
----------------+---------------------+---------------
+----------------
14.64      |         31.413      |     22.994    |      31.413

-----------------------------------------------------------------------
Fit based on last 3 points.

You may also look at -fracpoly- which fits fractional polynomials to

I'm not sure what the "significance" of a peak is, and I notice that
you have rather shyly surrounded it with quotes. What exactly do you
want to find out about the peak.

=========
Ron�n Conroy
[email protected]
+353 (0) 1 402 2431
+353 (0) 87 799 97 95
www.flickr.com/photos/ronanconroy

*
*   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/

*
*   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/
```