Description Usage Arguments Details Value Author(s) References See Also Examples

Computes the influence measure for a fitted spatial point process model.

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`model` |
Fitted point process model (object of class |

`...` |
Ignored. |

`drop` |
Logical. Whether to include ( |

`iScore,iHessian` |
Components of the score vector and Hessian matrix for the irregular parameters, if required. See Details. |

`iArgs` |
List of extra arguments for the functions |

Given a fitted spatial point process model `model`

,
this function computes the influence measure
described in Baddeley, Chang and Song (2013).

The function `influence`

is generic,
and `influence.ppm`

is the method for objects of class
`"ppm"`

representing point process models.

The influence of a point process model is a value attached to each data point
(i.e. each point of the point pattern to which the `model`

was fitted).
The influence value *s(x[i])* at a data point
*x[i]* represents the change in the maximised log (pseudo)likelihood
that occurs when the point *x[i]* is deleted.
A relatively large value of *s(x[i])* indicates a
data point with a large influence on the fitted model.

If the point process model trend has irregular parameters that were
fitted (using `ippm`

)
then the influence calculation requires the first and second
derivatives of the log trend with respect to the irregular parameters.
The argument `iScore`

should be a list,
with one entry for each irregular parameter, of **R** functions that compute the
partial derivatives of the log trend (i.e. log intensity or
log conditional intensity) with respect to each irregular
parameter. The argument `iHessian`

should be a list,
with *p^2* entries where *p* is the number of irregular
parameters, of **R** functions that compute the second order
partial derivatives of the
log trend with respect to each pair of irregular parameters.

The result of `influence.ppm`

is
an object of class `"influence.ppm"`

. It can be plotted
(by `plot.influence.ppm`

), or converted to a marked
point pattern by `as.ppp`

(see `as.ppp.influence.ppm`

).

An object of class `"influence.ppm"`

that can be plotted
(by `plot.influence.ppm`

). There are also methods
for `print`

, `[`

, `as.ppp`

and `as.owin`

.

.

Baddeley, A. and Chang, Y.M. and Song, Y. (2013)
Leverage and influence diagnostics for spatial point process models.
*Scandinavian Journal of Statistics* **40**, 86–104.

`leverage.ppm`

,
`dfbetas.ppm`

,
`ppmInfluence`

,
`plot.influence.ppm`

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spatstat documentation built on Jan. 30, 2018, 1:05 a.m.

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