Drawing on a case of infant deaths in a pediatric cardiac unit of a specialized hospital in Canada, we discussed how statistics was used to try to solve the unknown cause. A method of statistical analysis which was done by the epidemiologist and statistician was presented. The numbers of pediatric events, the hours on and off duty of certain nurses, the average number of deaths for each nurse when on duty and off duty , and with those averages being divided and standard deviations found, a number for each was generated. That number was evaluated in terms of probability of a person being responsible for an event.