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Analysing spatial point patterns in R - CSIRO

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26 Introduction to spatstat<br />

Interaction: Strauss process<br />

<strong>in</strong>teraction distance: 9<br />

Fitted <strong>in</strong>teraction parameter gamma: 0.2904<br />

Relevant coefficients:<br />

Interaction<br />

-1.236324<br />

We have fitted a model called the “Strauss <strong>po<strong>in</strong>t</strong> process” to these data. We can generate a<br />

simulated realisation of this model:<br />

> plot(simulate(fit))<br />

simulate(fit)<br />

Simulation 1<br />

We can perform a goodness-of-fit test for this fitted model:<br />

> plot(envelope(fit, Kest, nsim = 39))<br />

envelope(fit, Kest, nsim = 39)<br />

K(r)<br />

0 500 1000 1500<br />

obs<br />

mmean<br />

hi<br />

lo<br />

0 5 10 15 20<br />

r (one unit = 0.1 metres)<br />

This plot suggests good agreement between the model and the data.<br />

There are many, many other facilities for <strong>po<strong>in</strong>t</strong> process models <strong>in</strong> spatstat, described<br />

throughout these notes (ma<strong>in</strong>ly <strong>in</strong> Sections 15–16, 23.1, 27–28 and 34).<br />

Copyright<strong>CSIRO</strong> 2010

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