contr function

Create contrast matrix

Create contrast matrix typically for use with 'estimate' (Wald tests).

contr(p, n, diff = TRUE, ...)

Arguments

• p: index of non-zero entries (see example)
• n: Total number of parameters (if omitted the max number in p will be used)
• diff: If FALSE all non-zero entries are +1, otherwise the second non-zero element in each row will be -1.
• ...: Additional arguments to lower level functions

Examples

contr(2,n=5)
contr(as.list(2:4),n=5)
contr(list(1,2,4),n=5)
contr(c(2,3,4),n=5)
contr(list(c(1,3),c(2,4)),n=5)
contr(list(c(1,3),c(2,4),5))

parsedesign(c("aa","b","c"),"?","?",diff=c(FALSE,TRUE))

## All pairs comparisons:
pdiff <- function(n) lava::contr(lapply(seq(n-1), \(x) seq(x, n)))
pdiff(4)