# vcov.mppm

##### Calculate Variance-Covariance Matrix for Fitted Multiple Point Process Model

Given a fitted multiple point process model, calculate the variance-covariance matrix of the parameter estimates.

##### Usage

```
## S3 method for class 'mppm':
vcov(object, ..., what="vcov", err="fatal")
```

##### Arguments

- object
- A multiple point process model (object of class
`"mppm"`

). - ...
- Ignored.
- what
- Character string indicating which quantity should be calculated.
Either
`"vcov"`

for the variance-covariance matrix,`"corr"`

for the correlation matrix, or`"fisher"`

for the Fisher information matrix. - err
- Character string indicating what action to take if an error occurs.
Either
`"fatal"`

,`"warn"`

or`"null"`

.

##### Details

This is a method for the generic function `vcov`

.
The argument `object`

should be a fitted multiple point process
model (object of class `"mppm"`

) generated by `mppm`

.
The model must be a Poisson point process.
The variance-covariance matrix of the parameter estimates
is computed using asymptotic theory for maximum likelihood.
If `what="vcov"`

(the default), the variance-covariance matrix
is returned.
If `what="corr"`

, the variance-covariance matrix is normalised
to yield a correlation matrix, and this is returned.
If `what="fisher"`

, the Fisher information matrix is returned instead.

In all three cases, the rows and columns of the matrix correspond
to the parameters (coefficients) in the same order as in
`coef{model}`

.

These calculations are not available if the model is not Poisson,
or if it was computed using `gam`

. In such cases, the
argument `err`

determines what will happen. If
`err="fatal"`

an error will occur. If `err="warn"`

a warning will be issued and `NA`

will be returned.
If `err="null"`

, no warning is issued, but `NULL`

is returned.

##### Value

- A numeric matrix (or
`NA`

or`NULL`

).

##### See Also

##### Examples

```
data(waterstriders)
fit <- mppm(Wat ~x, data=hyperframe(Wat=waterstriders))
vcov(fit)
```

*Documentation reproduced from package spatstat, version 1.36-0, License: GPL (>= 2)*