R help - May 2010 - getting parts returned by lmer

R 2.10.0
windows XP

I am trying to get the coefficients returned from lmer. Normally I would use the
names function to get the objects returned by the function. This does not work
in lmer, but it does for lm:

 <- lmer(Reaction ~ Days + (1|Subject) + (0+Days|Subject),
sleepstudy)
> names(fm2)
NULL
> fitlm <- lm(Reaction ~ Days, sleepstudy)
> names(fitlm)
 [1] "coefficients"  "residuals"     "effects"    
"rank"
 [5] "fitted.values" "assign"        "qr"         
"df.residual"
 [9] "xlevels"       "call"          "terms"      
"model"

How does one know what is returned by lmer, and how does one access the various
parts? I looked at the code for lmer, but at least on my level of R
sophistication, the nature of the data returned in not clear.

Thanks,
John


John David Sorkin M.D., Ph.D.
Chief, Biostatistics and Informatics
University of Maryland School of Medicine Division of Gerontology
Baltimore VA Medical Center
10 North Greene Street
GRECC (BT/18/GR)
Baltimore, MD 21201-1524
(Phone) 410-605-7119
(Fax) 410-605-7913 (Please call phone number above prior to faxing)

Confidentiality Statement:
This email message, including any attachments, is for th...{{dropped:6}}

On May 3, 2010, at 9:41 AM, John Sorkin wrote:
> R 2.10.0
> windows XP
>
> I am trying to get the coefficients returned from lmer. Normally I  
> would use the names function to get the objects returned by the  
> function. This does not work in lmer, but it does for lm:
When you read the help page for lmer it refers your to the description  
of "mer"-class where that help page tells you that it is an S4 object
and offers a wide variety of extractor method functions, including a  
coef function. The str function would have shown you the slot names,  
but at your level of knowledge, it would probably be safer to work  
with the extractor/accessor functions. (I speak from sad experience.  
The authors of that package know a lot more than either of us.)

-- 
David.
>
> <- lmer(Reaction ~ Days + (1|Subject) + (0+Days|Subject), sleepstudy)
>> names(fm2)
> NULL
>
>> fitlm <- lm(Reaction ~ Days, sleepstudy)
>> names(fitlm)
> [1] "coefficients"  "residuals"     "effects"
"rank"
> [5] "fitted.values" "assign"        "qr"     
"df.residual"
> [9] "xlevels"       "call"          "terms"  
"model"
>
> How does one know what is returned by lmer, and how does one access  
> the various parts? I looked at the code for lmer, but at least on my  
> level of R sophistication, the nature of the data returned in not  
> clear.
>
> Thanks,
> John
>
>
> John David Sorkin M.D., Ph.D.
> Chief, Biostatistics and Informatics
> University of Maryland School of Medicine Division of Gerontology
> Baltimore VA Medical Center
> 10 North Greene Street
> GRECC (BT/18/GR)
> Baltimore, MD 21201-1524
> (Phone) 410-605-7119
> (Fax) 410-605-7913 (Please call phone number above prior to faxing)
>
> Confidentiality Statement:
> This email message, including any attachments, is for th...{{dropped: 
> 6}}
>
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