
Model Validation 421
contour map representing the fitted intensity (negative residuals). This carries all information about
discrepancies between the data and the model, but is often difficult to interpret — e specially in large
datasets or where the fitted intensity surface is complicated.
The bottom right panel is an image of the sm oothed residual field as in Figu re 11. 5. This
simplifies the information in the top left panel, drawing attention to parts of the window where
there is the greatest discrepancy between data and model. Positive values of the smoothed re sid ual
field would suggest that the fitted intensity is an underestimate of the true