negbin1 {addreg} | R Documentation |

## Family Functions for Negative Binomial 1 Models

### Description

Specifies the information required to fit a negative binomial 1 (NB1) model.

### Usage

```
negbin1(link, phi = stop("'phi' must be given"))
```

### Arguments

`link` |
included for compatibility with |

`phi` |
the value of the scale parameter of the NB1 distribution (see
"Details"). This can be set to |

### Details

The NB1 distribution can be parameterised in
terms of a mean `\mu`

and scale parameter `\phi`

(the
`phi`

argument of this function), such that if
`Y \sim NB1(\mu, \phi)`

, then `E(Y) = \mu`

and
`Var(Y) = (1+\phi)\mu`

.

These can be related to the `size`

and `prob`

arguments
of the `NegBinomial`

functions by `size`

= `\mu / \phi`

and `prob`

= `1 / (1 + \phi)`

.

### Value

An object of class `"family"`

: see `family`

for
full details. Note that when the estimate of `phi`

is updated in
a model, this `family`

object must be reloaded using the new
estimate.

### Author(s)

Mark W. Donoghoe markdonoghoe@gmail.com

*addreg*version 3.0 Index]