An object of class "vglmff" (see vglmff-class).
The object is used by modelling functions such as vglm,
and vgam.
Details
The Bell distribution
has a probability density function that can be written
$$f(y;s) = \frac{s^y \exp(1 - e^s) B_y}{y!} $$
for \(y=0(1)\infty\) and shape parameter \(0<s\).
The mean of \(Y\) is
\(\exp(s) s\)
(returned as the fitted values).
Fisher-scoring is used.
This VGAM family function handles multiple responses.
The function bell returns the first 218 Bell
numbers as finite numbers, and
returns Inf when its argument has a higher value.
Hence this VGAM family function can only handle low-value
counts of less than 219.
References
Castellares, F. and Ferrari, S. L. P. and Lemonte, A. J. (2018)
On the Bell distribution and its associated regression model for count data.
Applied Mathematical Modelling,
56, 172--185.