I would like to write a function that computes Tukey's 1 df for
nonadditivity. Here is a simplified version of the function I'd like to
write: (m is an object created by lm):
tukey.test <- function(m) {
m1 <- update(m, ~.+I(predict(m)^2))
summary(m1)$coef
}
The t-test for the added variable is Tukey's test. This won't work:
data(BOD)
m1 <- lm(demand~Time,BOD)
tukey.test(m1)
Error in predict(m) : object "m" not found
This function doesn't work for two reasons:
1. The statement m1 <- update(m, ~.+I(predict(m)^2)) can't see 'm' in
the call to predict.
2. If in creating m missing values had been present, then predict(m),
even if it could be computed, could be of the wrong length.
Can anyone help?
--
Sanford Weisberg, [EMAIL PROTECTED]
Office and mailing address:
University of Minnesota, School of Statistics
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612-625-8355, FAX 612-624-8868
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