glm.control {stats} | R Documentation

## Auxiliary for Controlling GLM Fitting

### Description

Auxiliary function for `glm` fitting. Typically only used internally by `glm.fit`, but may be used to construct a `control` argument to either function.

### Usage

    glm.control(epsilon = 1e-8, maxit = 25, trace = FALSE)

### Arguments

`epsilon` | positive convergence tolerance ε; the iterations converge when |dev - dev_{old}|/(|dev| + 0.1) < ε.
`maxit` | integer giving the maximal number of IWLS iterations.
`trace` | logical indicating if output should be produced for each iteration.

### Details

The `control` argument of `glm` is by default passed to the `control` argument of `glm.fit`, which uses its elements as arguments to `glm.control`: the latter provides defaults and sanity checking.

If `epsilon` is small (less than 1e-10) it is also used as the tolerance for the detection of collinearity in the least squares solution.

When `trace` is true, calls to `cat` produce the output for each IWLS iteration. Hence, `options(digits = *)` can be used to increase the precision, see the example.

### Value

A list with components named as the arguments.

### References

Hastie, T. J. and Pregibon, D. (1992) Generalized linear models. Chapter 6 of Statistical Models in S eds J. M. Chambers and T. J. Hastie, Wadsworth & Brooks/Cole.

### See Also

`glm.fit`, the fitting procedure used by `glm`.

### Examples

    ### A variation on  example(glm) :

    ## Annette Dobson's example ...
    counts <- c(18,17,15,20,10,20,25,13,12)
    outcome <- gl(3,1,9)
    treatment <- gl(3,3)
    oo <- options(digits = 12) # to see more when tracing :
    glm.D93X <- glm(counts ~ outcome + treatment, family = poisson(),
                    trace = TRUE, epsilon = 1e-14)
    options(oo)
    coef(glm.D93X) # the last two are closer to 0 than in ?glm's  glm.D93

[Package stats version 3.3.2 Index]