R: Extract Model Coefficients

coef {stats} | R Documentation

## Extract Model Coefficients

### Description

`coef` is a generic function which extracts model coefficients from objects returned by modeling functions. `coefficients` is an alias for it.

### Usage

    coef(object, ...)
    coefficients(object, ...)
    ## Default S3 method:
    coef(object, complete = TRUE, ...)
    ## S3 method for class 'aov'
    coef(object, complete = FALSE, ...)

### Arguments

`object` | an object for which the extraction of model coefficients is meaningful.
`complete` | for the default (used for `lm`, etc) and `aov` methods: logical indicating if the full coefficient vector should be returned also in case of an over-determined system where some coefficients will be set to `NA`, see also `alias`. Note that the default differs for `lm()` and `aov()` results.
`...` | other arguments.

### Details

All object classes which are returned by model fitting functions should provide a `coef` method or use the default one. (Note that the method is for `coef` and not `coefficients`.)

The `"aov"` method does not report aliased coefficients (see `alias`) by default where `complete = FALSE`.

The `complete` argument also exists for compatibility with `vcov` methods, and `coef` and `aov` methods for other classes should typically also keep the `complete = *` behavior in sync. By that, with `p <- length(coef(obj, complete = TF))`, `dim(vcov(obj, complete = TF)) == c(p,p)` will be fulfilled for both `complete` settings and the default.

### Value

Coefficients extracted from the model object `object`.

For standard model fitting classes this will be a named numeric vector. For `"maov"` objects (produced by `aov`) it will be a matrix.

### References

Chambers, J. M. and Hastie, T. J. (1992) Statistical Models in S. Wadsworth & Brooks/Cole.

### See Also

`fitted.values` and `residuals` for related methods; `glm`, `lm` for model fitting.

### Examples

    x <- 1:5; coef(lm(c(1:3, 7, 6) ~ x))

[Package stats version 4.0.5 Index]