# Weighted L-function (LW) test

The weighted L-function is a spatial test of goodness-of-fit of a spatial point process model. It is a centered and weighted version of Ripley's K-function, which is a popular statistic used to detect clustering or inhibition in spatial point patterns. The null hypothesis for the unweighted version assumes that the spatial point process is homogeneous Poisson, i.e. completely spatially random. The weighted version assumes that the point process follows some inhomogeneous model, in this case the model is a CSEP earthquake forecast, and the weighted L-function is used to detect if there is more or less clustering of earthquakes than what would be expected by the forecast.

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