[R] calculating std err (SEM)?

[Peter Dalgaard BSA]

"JRG" <loesljrg at accucom.net> writes:

> On 1 Mar 02, at 16:44, Peter Dalgaard BSA wrote:
> 
> > "Kirk R. Wythers" <kwythers at umn.edu> writes:
> > 
> > > Is there a "canned" function in R for finding the standard error of the
> > > mean? I have tried 
> > > 
> > > >  sem <- function(x) c(mean =mean(x),
> > > +  SEM = stdev(x)/sqrt(length(x)))
> > > > sem(pnet.lai)
> > > Error in sem(pnet.lai) : couldn't find function "stdev"
> > > 
> > > 
> > > It looks like there is no stdev function in R
> > 
> > It's sd() (as help.search("deviation") might have told you). Also,
> > beware of missing values:  sd(x,na.rm=TRUE)/sum(!is.na(x)) is the sure
> > kill. 
> > 
> 
> Would that perhaps be  sd(x,na.rm=TRUE)/sqrt(sum(!is.na(x))) ?

Um. Yes.

On the other hand, I didn't say *what* it killed, did I? ;-)

        -p

-- 
   O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
 (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)             FAX: (+45) 35327907
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