Dear Martin,
It's possible that the GLM procedure of SAS with HELMERT in the REPEATED
may respond to your question, because, HELMERT permits to COMPARE each
level of the factor (the within=time in this case) with the MEAN of the
subsequent levels.
In the output: "Analysis of contrast variables"
you can see the level of significant (p value),
You can consider that the plateau is reached at time where
the p value become not significant.
But if you want to see that for each treatment, you must specify
the "By treatment" statement in Proc GLM and replace the statement
"model Y1-Y7 = treatment /nouni" by "model model Y1-Y7 = /nouni"
NB.
I think, that you must begin by plotting Y versus time by treatment to look
if you can expect a plateau from your data.
Good luck.
Hassane
|=======================================================|
| Hassane ABIDI (PhD) |
| Unite d'Epidemiologie; Centre Hospitalier Lyon-Sud |
| Pavillon 1.M, 69495 Pierre Benite Cedex, France |
| Tel: (33) 04 78 86 56 87 ; Fax: (33) 04 78 86 33 31 |
| E. mail: [EMAIL PROTECTED] |
|=======================================================|
[EMAIL PROTECTED] wrote:
>
> I have the following problem ...
>
> I have 5 treatments measured at 7 time
> intervals.
>
> How can I answer the following question: "At
> which point does each treatment reaches a
> plateau?"?
>
> I think this question can be answered by the PROC
> GLM procedure in SAS with HELMERT in the REPEATED
> statement.
>
> model Y1-Y7 = treatment /nouni
> repeated vis 7 helmert / canon printm printe;
>
> Am I right? If yes, how do I interpret the SAS
> output? Is there a p-value associated with the
> question "At which point does each treatment
> reaches a plateau?"?
>
> Thank you,
>
> Martin
>
> Sent via Deja.com http://www.deja.com/
> Before you buy.
>
> ===========================================================================
> This list is open to everyone. Occasionally, less thoughtful
> people send inappropriate messages. Please DO NOT COMPLAIN TO
> THE POSTMASTER about these messages because the postmaster has no
> way of controlling them, and excessive complaints will result in
> termination of the list.
>
> For information about this list, including information about the
> problem of inappropriate messages and information about how to
> unsubscribe, please see the web page at
> http://jse.stat.ncsu.edu/
> ===========================================================================
===========================================================================
This list is open to everyone. Occasionally, less thoughtful
people send inappropriate messages. Please DO NOT COMPLAIN TO
THE POSTMASTER about these messages because the postmaster has no
way of controlling them, and excessive complaints will result in
termination of the list.
For information about this list, including information about the
problem of inappropriate messages and information about how to
unsubscribe, please see the web page at
http://jse.stat.ncsu.edu/
===========================================================================
