The L(ikelihood)-test

The L(ikelihood)-test measures the consistency of a forecast with the observed rate and spatial/magnitude distribution of earthquakes. The joint log-likelihood of the observed catalog conditional on the forecast is omputed,  and this value is compared with the expected distribution of joint log-likelihoods assuming that the forecast is correct. If the joint log-likelihood of the observed catalog is exceedingly low relative to the expected distribution, this indicates that the forecast has not predicted well the distribution of earthquakes.