Standard radioactive decay occurs exponentially at a constant rate which, apart from a few wellunderstood exceptions, is unaffected by external conditions. Recent papers challenging standard decay have reported periodic variations in the decay rate of certain nuclei that correlate with geophysical or astrophysical periodicities. The effects are weak and their origins have been disputed. This paper proposes an alternative method to search for non-standard radioactive decay based on the distribution of decay events, rather than on deviations from the exponential decay law. It is shown that a time series of nuclear decays comprise a Mixed Poisson-Gauss distribution whose probability function is very sensitive to periodic variations in the decay rate.