niters {VGAM} | R Documentation |
Number of Iterations
Description
Extracts the number of IRLS iterations performed for a VGLM object.
Usage
niters(object, ...)
niters.vlm(object, history = FALSE, ...)
Arguments
object |
A |
history |
Logical, if |
... |
Currently unused. |
Details
The number of iteratively reweighted least squares (IRLS) iterations needed for convergence (or non-convergence) does say something about the model. Since Fisher scoring has a linear convergence rate in general, it should take no more than 10 iterations, say, for successful convergence. Much more indicates potential problems, e.g., a large disagreement between data and the specified model.
Value
A non-negative integer by default.
If history = TRUE
then a matrix.
Note
Step-halving may or may not affect the answer.
See Also
Examples
fit <- vglm(rpois(9, 2) ~ 1, poissonff, crit = "c")
niters(fit)
niters(fit, history = TRUE)