pgirmess (version 2.0.3)

PermTest: Permutation test for lm, lme and glm (binomial and Poisson) objects

Description

Permutation test for lm, lme and glm (binomial and Poisson) objects

Usage

PermTest(obj, B=1000,...)
    # S3 method for lm
PermTest(obj, B=1000,...)
    # S3 method for lme
PermTest(obj, B=1000,...)
    # S3 method for glm
PermTest(obj, B=1000,...)

Value

A list object of class PermTest including:

p.value

the p value obtained

B

the number of permutations

call

the call

Arguments

obj

an object of class lm, lme, or glm

B

number of permutations, default = 1000

...

used to pass other arguments

Warning

This generic function is implemented in R language, thus can be quite slow.

Details

For glm, when the response is a two-column matrix with the columns giving the numbers of successes and failures, PermTest.glm uses permcont(); PermTest.lme requires the library nlme.

Examples

if(require(MASS)){
mylm<-lm(Postwt~Prewt,data=anorexia)
PermTest(mylm,B=250)


## Dobson (1990) Page 93: Randomized Controlled Trial :
    counts <- c(18,17,15,20,10,20,25,13,12)
    outcome <- gl(3,1,9)
    treatment <- gl(3,3)
    glm.D93 <- glm(counts ~ outcome + treatment, family=poisson)
    PermTest(glm.D93,B=100)
    }

if(require(nlme)){
fm2 <- lme(distance ~ age + Sex, data = Orthodont, random = ~ 1)
PermTest(fm2,B=100)
}