find the corresponding mean y

Annie,

If I understand what you are asking, you want to sample some number of 
observations, with replacement, then find the mean of x and y for those 
observations.

In this case, you would want to sample the row indices instead of the 
values. For example,

     #test data
set.seed(1)
df <- data.frame(x = rnorm(100), y = rnorm(100))
     #sample from row indices
samp <- sample(nrow(df), 25, replace = TRUE)

     #get means for x and y
mean(df[samp,]$x)
mean(df[samp,]$y)
     #or
mean(df[samp,])

Greg

Hello, I have 49 paired data, x, y.
I have sampled x (where replacement is true), and find its mean.
How can I find the corresponding mean y, which is the paired data of above
sample x?
Thank you very much,
Annie
   

Greg Hirson
ghirson at ucdavis.edu

Graduate Student
Agricultural and Environmental Chemistry

1106 Robert Mondavi Institute North
One Shields Avenue
Davis, CA 95616