Compute Allowed Changes in Adding to or Dropping from a Formula
Usage
add.scope(terms1, terms2)
drop.scope(terms1, terms2)
factor.scope(factor, scope)
Arguments
terms1
|
the terms or formula for the base model.
|
terms2
|
the terms or formula for the upper (add.scope) or
lower (drop.scope) scope. If missing for drop.scope it is
taken to be the null formula, so all terms (except any intercept) are
candidates to be dropped.
|
factor
|
the "factor" attribute of the terms of the base object.
|
scope
|
a list with one or both components drop and
add giving the "factor" attribute of the lower and
upper scopes respectively.
|
Description
add.scope and drop.scope compute those terms that can be
individually added to or dropped from a model while respecting the
hierarchy of terms.Details
factor.scope is not intended to be called directly by users.Value
For add.scope and drop.scope a character vector of
terms labels. For factor.scope, a list with components
drop and add, character vectors of terms labels.Author(s)
B.D. RipleySee Also
add1, drop1,
aov, lmExamples
add.scope( ~ a + b + c + a:b, ~ (a + b + c)^3)
# [1] "a:c" "b:c"
drop.scope( ~ a + b + c + a:b)
# [1] "c" "a:b"