[datatable-help] Contrast matrix with a continuous variable

[Arunkumar Srinivasan]

This is the mailing list for R’s data.table package. Please post on r-help mailing list.

-- 
Arun

On 22 May 2016 at 10:44:29, CRoa (carlosalvarezroa at hotmail.com) wrote:

Hi all,  
I was wondering if someone could help me designing a contrast matrix when  
you have a continuous variable (Days).  

My model looks like this:  

model<-lme(Y~A*B*Days, data=data_over_time)  

The factor A has two levels (A1 and A2) and factor B has three levels (B1,  
B2, and B3). I measured the response variable Y every two or three days over  
70 days (Days).  
I need to look at only a few comparisons over the 70 days such us:  
A1 and B1 vs A2 and B1,  
A2 and B2 vs A2 and B1,  
A1 and B2 vs A2 and B2  
I could use the function contrast from the package contrast to design the  
matrix with the three comparisons mentioned above for specific days at a  
time. However, I need to run the comparison over the 70 days not at  
individual time points.  

I was wondering if someone could help me designing this contrast matrix.  

Any help would be much appreciated  
Cheers  



--  
View this message in context: http://r.789695.n4.nabble.com/Contrast-matrix-with-a-continuous-variable-tp4720966.html  
Sent from the datatable-help mailing list archive at Nabble.com.  
_______________________________________________  
datatable-help mailing list  
datatable-help at lists.r-forge.r-project.org  
https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/datatable-help  
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.r-forge.r-project.org/pipermail/datatable-help/attachments/20160522/e77fac71/attachment.html>