pvalue-from-lm-object.r

pvalue-from-lm-object.r

# Function to extract the overall ANOVA p-value out of a linear model object
lmp <- function (modelobject) {
	if (class(modelobject) != "lm") stop("Not an object of class 'lm' ")
	f <- summary(modelobject)$fstatistic
	p <- pf(f[1],f[2],f[3],lower.tail=F)
	attributes(p) <- NULL
	return(p)
}

# simulate some data
set.seed(42)
n=20
d=data.frame(x1=rbinom(n,2,.5), x2=rbinom(n,2,.5))
d=transform(d, y=x1+x2+rnorm(n))

#fit the linear model
fit=lm(y ~ x1 + x2, data=d)

summary(fit) #shows that the F-test is 0.006641

names(summary(fit)) #can't access that p-value using this!
names(fit) # this doesn't work either

lmp(fit) # uses the above function to capture the F-test p-value.