I have three clinics that are testing for Zika virus. We know the proportion of positives aggregated across all clinics, i.e., the first clinic has identified 20% of all positives across the three clinics, the second 30% and the third 50%. Now we know there are 100 new cases but these proportions change with respect to previous cases, i.e., they are now 10% 50% and 40%. Is there a distribution that can tell me if these proportions are significantly different than would be expected given the original proportions? I have run a Monte Carlo simulation to figure this out, but I was wondering if there was a distribution that describes this.