From: Kerry Bush <kerryrekky_at_yahoo.com>

Date: Thu 16 Jun 2005 - 01:40:58 EST

R-help@stat.math.ethz.ch mailing list

https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Thu Jun 16 01:46:28 2005

Date: Thu 16 Jun 2005 - 01:40:58 EST

Dear helpers in this forum,

This is a clarified version of my previous questions in this forum. I really need your generous help on this issue.

> Suppose I have the following data set:

*>
**> id x y
**> 023 1 2
**> 023 2 5
**> 023 4 6
**> 023 5 7
**> 412 2 5
**> 412 3 4
**> 412 4 6
**> 412 7 9
**> 220 5 7
**> 220 4 8
**> 220 9 8
**> ......
**>
*

Now I want to compute the following double summation:

sum_{i=1}^k

sum_{j=1}^{n_i}(x_{ij}-mean(x_i))*(y_{ij}-mean(y_i))

i is from 1 to k,

indexing the ith subject id; and j is from 1 to n_i,
indexing the jth observation for the ith subject.

in the above expression, mean(x_i) is the mean of x
values for the ith

subject, mean(y_i) is the mean of y values for the ith
subject.

Is there a simple way to do this in R?

R-help@stat.math.ethz.ch mailing list

https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Thu Jun 16 01:46:28 2005

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