[R] Fwd: Calculating group means

[arun]

Hi,
You could either try:
#dat1 ##dataset
aggregate(latency~.,data=dat1,mean)

#or
 library(data.table)
 dt1 <- data.table(dat1,key=c('subject','conditionNo','state'))
 dt1[,mean(latency),by=c('subject','conditionNo','state')]

A.K.




On Monday, December 23, 2013 2:20 PM, Laura Bethan Thomas [lbt1] <lbt1 at aber.ac.uk> wrote:
> Hi All, 
> 
> Sorry for what I imagine is quite a basic question. I have been trying to do is create latency averages for each state (1-8) for each participant (n=13) in each condition (1-10). I'm not sure what function I would need, or what the most efficient ay of calculating this would be. If you have any help with that I would be very grateful.
> 
> structure(list(subject = c(1L, 1L, 1L, 1L, 1L, 1L), conditionNo = c(1L, 
> 1L, 1L, 1L, 1L, 1L), state = c(5L, 8L, 7L, 8L, 1L, 7L), latency = c(869L, 
> 864L, 1004L, 801L, 611L, 679L)), .Names = c("subject", "conditionNo", 
> "state", "latency"), row.names = 3:8, class = "data.frame")
> 
> Thanks again,
> 
> Laura

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