  We describe a statistical hypothesis test for the presence of a signal based
on the likelihood ratio statistic. We derive the test for a special case of
interest. We study extensions of the test to cases where there are multiple
channels and to marked Poisson distributions. We show the results of a number
of performance studies which indicate that the test works very well, even far
out in the tails of the distribution and with multiple channels and marked
Poisson.
