[R] Treatment-Contrast Interactions

[Peter Dalgaard]

Lorin Hochstein <lorin at cs.umd.edu> writes:

> I'd like to understand this approach as well, but I can't reproduce my
> results using se.contrast. In particular, I get the same standard
> error even though I tried to use different contrasts:
> 
>  > c1 <- c(1,-1)[A]*c(1,-1,0)[B]
>  > c2 <- c(1,-1)[A]*c(1,0,-1)[B]
>  > c3 <- c(1,-1)[A]*c(0,1,-1)[B]
>  > se.contrast(fit, as.matrix(c1))
> Contrast 1
>   14.24547
>  > se.contrast(fit,as.matrix(c2))
> Contrast 1
>   14.24547
>  > se.contrast(fit,as.matrix(c3))
> Contrast 1
>   14.24547

They could well _be_ the same if the design is balanced...
 
-- 
   O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
 (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)             FAX: (+45) 35327907