Source:http://linkedlifedata.com/resource/umls/id/C0032347
MSH: A distribution function used to describe the occurrence of rare events or to describe the sampling distribution of isolated counts in a continuum of time or space.,NCI: A distribution function used to describe the occurrence of rare events or to describe the sampling distribution of isolated counts in a continuum of time or space. This special probability distribution can apply to the number of discrete independent random events occurring in a given interval when knowing their average rate of occurrence over a very long interval. (Dr. Joseph A. Thie)