statistical monitoring of rare events in healthcare

there are miscellaneous quality characteristics in healthcare which are interested to be monitored. however, monitoring each characteristic needs a special statistical method. there are some characteristics with very small incidence rates that it’s usually considered not to be necessary to monitoring them, since their incidence rates are so small that p and np charts are not able to monitor them. such characteristics are called “rare health-related events”. in this paper, while introducing the most common methods for monitoring the rare events, we are going to compare their performances based on the average run length (arl) .