Re: [R] Estimating correlation in multiple measures data

2011-03-24 Thread Michal Figurski
Peter, Regarding 1) I do not agree. See the following, simplified example: x <- data.frame(ID=rep(1:2, each=4), Visit=rep(c(1:4), 2), ptA=c(7,8,9,10,17,18,19,20), ptB=c(5,6,7,8,21,20,19,18)) In this data frame you have only 2 patients with 4 visits each, but the correlation of ptA and ptB is

Re: [R] Estimating correlation in multiple measures data

2011-03-23 Thread Peter Langfelder
On Wed, Mar 23, 2011 at 1:17 PM, Michal Figurski wrote: > Dear R-helpers, > > This may sound simple to you, but I'm a beginner in this, so please be > forgiving. > I have a following problem: two analytes were measured in patient's blood on > 4 occasions: ProteinA and ProteinB. How to correctly ev

[R] Estimating correlation in multiple measures data

2011-03-23 Thread Michal Figurski
Dear R-helpers, This may sound simple to you, but I'm a beginner in this, so please be forgiving. I have a following problem: two analytes were measured in patient's blood on 4 occasions: ProteinA and ProteinB. How to correctly evaluate correlation between ProteinA and ProteinB? I tried: x <