Handling cause of death in equivocal cases using the em algorithm

The statistical analysis of animal bioassays fore carcinogenicity often involves utilizing the cause of death of each animal. There is considerable disagreement among veterinary pathologists as to the reliability of cause of death information. Recent recommendations for assigning cause of death in animal studies have allowed for uncertainty on the part of the pathologist. This has given rise to data that contain acknowledged equivocal cases with respect to cause of death. The present paper proposes a method for incorporating these equiYocal cases into an existing estimation procedure that requires distinguishing between tumors that caused death and those that did not.