conf.set {conf.design}R Documentation

Find confounded effects.

Description

Find minimal complete sets of confounded effects from a defining set for symmetric confounded factorial designs. Useful for checking if a low order interaction will be unintentionally confounded with blocks. As in the usual convention, only effects whose leading factor has an index of one are listed.

Usage

conf.set(G, p)

Arguments

G Matrix whose rows define the effects to be confounded with blocks, in the same way as for conf.design().
p Number of levels for each factor. Must be a prime number.

Details

The function constructs all linear functions of the rows of G (over GF(p)), and removes those rows whose leading non-zero component is not one.

Value

A matrix like G with a minimal set of confounded with blocks defined in the rows.

Side Effects

None

See Also

conf.design

Examples

 G <- rbind(c(1,2,1,0), c(0,1,1,1))
 dimnames(G) <- list(NULL, LETTERS[1:4])
 conf.set(G, 3)
 #     A B C D 
 # [1,] 1 2 1 0
 # [2,] 0 1 1 1
 # [3,] 1 0 2 1
 # [4,] 1 1 0 2
 # If A B^2 C and B C D are confounded with blocks, then so are A C^2 D
 # and A B D^2.  Only three-factor interactions are confounded, so the
 # design is presumably useful.