calculating std err (SEM)?

"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))) ?

---JRG


John R. Gleason

Syracuse University
430 Huntington Hall                      Voice:   315-443-3107
Syracuse, NY 13244-2340  USA             FAX:     315-443-4085

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