Residual analysis for spatial point processes
نویسندگان
چکیده
We define residuals for point process models fitted to spatial point pattern data, and propose diagnostic plots based on them. The residuals apply to any point process model that has a conditional intensity; the model may exhibit spatial heterogeneity, interpoint interaction and dependence on spatial covariates. Some existing ad hoc methods for model checking (quadrat counts, scan statistic, kernel smoothed intensity, Berman’s diagnostic) are recovered as special cases. Diagnostic tools are developed systematically, using an analogy between our spatial residuals and the usual residuals for (non-spatial) generalised linear models. The conditional intensity λ plays the role of the mean response. This makes it possible to adapt existing knowledge about model validation for GLM’s to the spatial point process context, giving recommendations for diagnostic plots. A plot of smoothed residuals against spatial location, or against a spatial covariate, is effective in diagnosing spatial trend or covariate effects. Q–Q plots of the residuals are effective in diagnosing interpoint interaction.
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