Behalf Of Bruno Estigarribia
Sent: January-22-09 12:32 AM
To: r-help at r-project.org
Subject: [R] Standard errors of least squares adjusted means
Hello,
I have the following model:
lm.7 <- lm(Y ~ F + C1 + C2 , data = EM4)
F is a 4-level factor, the rest are covariates centered at their mean (Y
is a two-column matrix).
I have tried to find functions to give the model-adjusted means
(adjusted at the covariates'means) and their standard deviations for each.
(That is, what I believe is called in SAS "least square or LS-means,
whose errors one obtains by STDERR)
I have tried help.search and RSiteSearch with several terms including
"standard errors", "least square means", "adjusted means". I have found
how to extract the SE from coefficients (se.coef from package arm), or
the SE for contrasts (se.contrast from package stats), but not the SE
for an adjusted mean.
Thank you,
--
Bruno Estigarribia
Postdoctoral Fellow
FPG Child Development Institute
Neurodevelopmental Disorders Research Center
University of North Carolina at Chapel Hill
105 Smith Level Rd
Chapel Hill, NC 27599-8180
USA
+ 1 (919) 843-7685