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Measurement Error in County-Level UCR Data

NCJ Number
200487
Journal
Journal of Quantitative Criminology Volume: 19 Issue: 2 Dated: June 2003 Pages: 185-198
Author(s)
John R. Lott Jr.; John Whitley
Date Published
June 2003
Length
14 pages
Annotation
This article discusses measurement error in county-level data on right-to-carry gun laws.
Abstract
A paper by Maltz and Targonski in 2002 notes that not all police jurisdictions in a county report their crime data. This produces measurement error in the county-level dataset derived from these reports. Some of the measurement problems apparent in the county-level data will also be present in the State-level data. They argue that measurement error brings existing research on gun laws that used this data into question. But they do not directly test if it affects the results. This study focused on the impact that these data problems have on right-to-carry laws. Gun control work uses regressions weighted by population. The conclusion by Maltz and Targonski that county-level crime data should not be used is not justified. All data has measurement error. Their graphs obscure both the small number of counties affected, that these are rural counties, and that just because some of the population in a county is not represented in calculating the crime rate, that is not the same thing as showing that the reported number is in error. They do not provide evidence for the more important issue of whether there is a systematic bias in the data. The evidence provided in this study indicates right-to-carry laws continue to produce substantial reductions in violent crime rates when States with the greatest measurement error are excluded. Restricting the sample results in somewhat larger reductions in murders and robberies, but smaller reductions in aggravated assaults. Previous research on guns and crime has used different types of Uniform Crime Report data to test whether the results were sensitive to the type of data used. The consistent results indicated that there was not a systematic problem with the county data. 1 table, 5 figures, 14 footnotes, 11 references