Hi Isabelle-Anne,
The type of test you need to use is a repeated measures analysis,
because it takes into account treatment factors as well as change over
time on the same individual subjects. Repeated measures analysis is a
class of linear mixed models, because time is a random effect while
the treatment factors are fixed effects. (I assume you are using a
control group.)
For contemporary linear mixed models using SAS, I recommend the
following sources:
Littell, R.C., Milliken, G.A., Stroup, W.W., Wolfinger, R.D.,
Schabenbarger O., 2006. SAS® for Mixed Models, 2nd edn. SAS Institute,
Cary, North Carolina.
Littell, R.C., Stroup, W.W., Freund, R.J., 2002. SAS? for Linear
Models, 4th edn. SAS Institute, Cary, North Carolina.
Schabenberger, O., Pierce, F.J., 2002. Contemporary Statistical Models
for the Plant and Soil Sciences. CRC Press, Boca Raton, Florida.
Good luck, Don
--
Don Campanella, Ph.D. Dept. of Botany and Plant
Pathology
[email protected] Oregon State
University
Date: Thu, 11 Jun 2009 17:54:35 -0400
From: =?iso-8859-1?Q?Isabelle-Anne_Bisson?= <[email protected]>
Subject: Mixed Linear Models
Fellow Eco-loggers,
I would greatly appreciate your input on a statistical question that I
have. My study design is as follows:
Four subjects receive NO treatment on day 1 and a treatment on day 2. The
treatment is of 4 hours. I take a measurement (e.g., blood pressure) every
minute for each subject on both days. I would like to test for the effect
of treatment while taking into account change over time. Are 'linear mixed
models' analyses appropriate for this type of data set?
I will gladly provide more information if need be.
Thank you,
Isabelle
