AcrossTic (version 1.0-3)

ptest: Permutation test for AcrossTic objects

Description

This function permutes the "y" entries in an AcrossTic object and computes the cross-count statistic for each permutation. This generates a null distribution suitable for use in a permutation test.

Usage

ptest(acobj, y, edge.weights, n = 1000)

Arguments

acobj

Object of class AcrossTic, output from rRegMatch.

y

Character, factor or logical indicating class membership for each observation. Normally this will be found inside acobj.

edge.weights

Vector of weights associated with each match. If omitted, the default is a vector of 1's of the proper length, unless the "acobj" object was computed with partial matching, in which case omitting edge.weights produces an error.

n

Integer, number of simulations. Default, 1000.

Value

A list with class AcrossTicPtest and three components: A list with class AcrossTicPtest and three components:

Details

This function permutes the y's n times and computes the cross-count-match statistic. If the observed value in the acobj is generally smaller than the permuted values, we conclude the distributions of the classes are different.

See Also

rRegMatch

Examples

set.seed (123)
X <- matrix (rnorm (100), 50, 2) # Create data...
y <- rep (c ("One", "Two"), each=25) # ...and class membership
## Not run: ptest (rRegMatch (X, r = 3, y = y)) # p = .479
X[1:25,] <- X[1:25,] + 1
## Not run: ptest (rRegMatch (X, r = 3, y = y)) # p = .037