factor.scope {stats} | R Documentation |

## Compute Allowed Changes in Adding to or Dropping from a Formula

### 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.

### 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. |

### 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.

### See Also

`add1`

, `drop1`

,
`aov`

, `lm`

### Examples

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"

[Package

*stats* version 2.5.0

Index]