ztpoisson | R Documentation |

Family object for specification of zero-truncated Poisson models
as a `glm`

.

```
ztpoisson()
```

The `ztpoisson`

family allows to estimate zero-truncated
Poisson regression models as generalized linear models. As in
the `zerotrunc`

function, the link function is a
log-link between the mean `\lambda`

of the untruncated Poisson
distribution and the linear predictor. This corresponds to a
non-canonical link between for the mean of the zero-truncated
Poisson distribution which does not have a closed-form representation.

Note that for new family objects 'glm()' estimates a dispersion
parameter by default. Thus, unlike for the `poisson`

family the dispersion parameter is not fixed, unless `dispersion = 1`

is set explicitly .

An object of class `"family"`

.

`dztpois`

, `poisson`

,
`zerotrunc`

```
## data
data("CrabSatellites", package = "countreg")
cs <- subset(CrabSatellites, subset = satellites > 0)
cs$color <- as.numeric(cs$color)
## model
ztp1 <- glm(satellites ~ width + color, data = cs, family = ztpoisson)
ztp2 <- zerotrunc(satellites ~ width + color, data = cs)
summary(ztp1, dispersion = 1) ## to get fixed dispersion as for poisson
summary(ztp2)
```

Embedding an R snippet on your website

Add the following code to your website.

For more information on customizing the embed code, read Embedding Snippets.