bftest {ALSM}

Brown-Forsythe Test between two group

Description

Tests for Constancy of Error Variance between two group

Usage

bftest(fit,group,alpha=.05)

Arguments

fit

model of regression

group

vector, determine two group

alpha

Type I error level

Details

length group and number of observations should be equal

Value

test statistic, p.value, alpha and degree of freedom

References

Michael H. Kutner; Christopher J. Nachtsheim; John Neter; William Li. Applied Linear Statistical Models Fifth Edition .page 116

Examples

################### EXAMPLE PAGE 117


### Group
g<-rep(1,25)
g[TolucaCompany$x<=70]=0
### TEST
bftest(lm(y~x,TolucaCompany),g)