The validity of robbery-murder classifications in Baltimore

The most widely used source of nationwide data on homicide in the United States is the Supplementary Homicide Report (SHR) data compiled by the FBI as part of its Uniform Crime Reporting System. This paper describes a study of the reliability of robbery-murder classifications by the SHR for Baltimore, Maryland during 1983. The research is exploratory, but indicates a high level of inconsistency in the data. Of the 42 cases that were classified as robbery murders by the SHR or the replication study, only 20 were classified that way in both studies. The high level of unreliability can be attributed to three major problems: (1) the SHR codes are mutually exclusive, but many homicides could be placed in several of the categories; (2) there are few systematic rules for classifying ambiguously motivated homicides; and (3) the SHR placed too many cases in the "unknown" category. It appears that the reliability of the coding could be increased substantially with relatively minor changes in the procedures currently used.