Hi chipmaney,
Here is a suggestion:

with(data, tapply(value, group, function(x) sd(x)/sqrt( length(x) ) ) )
* sqrt(fc$fc)

BTW, take a look at

require(fortunes)
fortune('dog')

HTH,
Jorge


On Tue, Sep 29, 2009 at 6:29 PM, chipmaney <> wrote:

>
> #I have these data. Basically, I want to run a tapply to calculate the mean
> and st. err. by factor.
> #The problem is, I want to add a finite correction to the variance prior to
> calculating the standard error.
> #Now I know I could just do this in 3/4 steps by calculating the var,
> applying the correction, then calculating the StErr.
>
> #However, I am trying to learn about functions and how they work. So if you
> interested in puzzling the #following problem out..........
>
> #I want to integrate the fc into the tapply()
> #Since the fc is a different object than the tapply() object, how do I
> integrate the fc into the function()
> #call for the St.Err so that i get the formula (  fc*var(x)/length(x)
>  )^0.5
> for each factor????
> #I believe this takes some fidgeting with function(x), but I suck at
> function building,
> #particularly in this case of embedding a function() with multiple inputs
> into an R function with only 1 #input,
> #so I need help...maybe i need to input the tapply() function into my own
> built function???? I don't know.
>
>
>
> data <- data.frame(group = c(rep("A",4), rep("B",5)), value =
> c(40,45,24,34,234,243,435,324,244) )
> fc <- data.frame(group=c("A","B"), fc = c(0.75, 0.85))
>
> Mean <- tapply(data$value,data$group, mean)
> StErr <- tapply(data$value,data$group, function(x) ( var(x)/length(x) )^0.5
> ) #no fc yet
>
> --
> View this message in context:
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> Sent from the R help mailing list archive at Nabble.com.
>
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