Quality of Chicago Supplementary Homicide Reports Data Compared to the Chicago Homicide Dataset

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Quality of Chicago Supplementary Homicide Reports Data Compared
to the Chicago Homicide Dataset
Carolyn Rebecca Block, Thomas D. Patterson and Daniel Dick
Illinois Criminal Justice Information Authority
September 13, 1999
The Supplementary Homicide Reports (SHR) of the Uniform Crime Reports
has been for many years a foundation of homicide research In the United States
(Maltz, 1999). The SHR is easily accessible, available in the National Archive of
Criminal Justice Data (Fox, 1996), and contains more detail about each incident than
available in the Uniform Crime Reports for other violent crimes. Policy decision-makers
depend upon it to answer such basic questions as the trends in homicide
rates of young offenders (Fox, 1997), the effectiveness of gun-carry laws (Lott &
Mustard, 1997), the risk of death due to child abuse (Maltz, 1998), the number of
domestic violence homicides (Langford, et al., 1998), or the proportion of homicides
committed by a stranger (Riedel, 1998; Williams & Flewelling, 1987).
Since the SHR has been and continues to be the source of much of our know-ledge
about lethal violence in the United States, it is important to know just how good
that source is. Is the SHR complete enough and accurate enough to be a basis of
policy decisions? To evaluate the completeness and accuracy of SHR data in one
city, the Bureau of Justice Statistics (BJS) asked the Illinois Criminal Justice Informa-tion
Authority to conduct a case-by-case comparison of the 1,784 homicides recorded
in the Chicago Homicide Dataset (CHD) in 1993 or 1994 to homicides recorded in the
SHR for those years. BJS wanted to know whether SHR data on offender characteris-tics
was systematically different from data in police files, and if so, to describe those
differences. The results provide information about the quality of SHR data in Chicago,
and by extension, about SHR quality in other cities with similar situations.
Methodology
Case-by-Case Completeness and Accuracy
Maltz (1999:35) defines complete as the degree to which the SHR contains all
of the homicide cases contained in some comparison data file or set of data files.
Data sets used as a standard of comparison have included data collected by the
National Center for Health Statistics (Riedel, 1990, 1993; 1999; Rand, 1993; Rokaw,
et al., 1990), monthly Uniform Crime Reports totals (Snyder, 1996:10-11; Bailey &
Peterson, 1995: 184), detailed police records (Maxfield, 1989), and public health or
court records (Langford, et al., 1998). However, with two exceptions (Rand, 1993 and
Langford, et al., 1998), these comparisons have been based on monthly or yearly
totals. The results of both of the exceptions demonstrate the danger of relying on
totals as an indicator of completeness. Like them, the Chicago analysis was based a
case-by-case comparison. We attempted to find the matching homicide in the SHR for
each homicide in the CHD that was booked in 1993 or 1994.
A homicide is not necessarily entered into police records (booked) as a homi-cide
on the same day that the incident occurs. The victim may die the next day or
even years after the attack that caused the death. In addition, the police or medical