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Effects of the Police on Crime - A Second Look

NCJ Number
Date Published
January 1981
14 pages
This study of the effect of aggressive policing on the robbery rate in nine cities during the period from 1948 to 1978 shows that police activity may actually increase the recorded robbery rate.
The cities examined here were Atlanta, Boston, Houston, Minneapolis, Philadelphia, Newark (N.J.), Phoenix (Ariz.), and Oakland and San Jose (Calif.). The data came from published sources and from unpublished agency records collected by field staff. A sequential relationship between police aggressiveness and a decline in the robbery rate was sought. A number of indicators of governmental responses to crime in general and to robbery in particular were examined. For example, a city could expand its police force; in addition, it could become more aggressive. The number of moving violations (suggested by an earlier, 1978 study) and an increase in the number of arrests for serious offenses were used as measures of police aggressiveness. The measures more directly related to robbery incidents were the number of adult and juvenile robbery arrests in terms of their frequency for each police officer and in terms of their number relative to all other arrests for major crimes. The data showed that, contrary to the 1978 study, police activity increased the recorded robbery rate (in six cities). Possibly, as police become more concerned with robberies, citizens were induced to report more robberies, and, perhaps led the police to record more offenses as robberies. A strong evidence was also found against the use of moving violations as an indicator of police aggressiveness. Moving violations followed the same path as robbery only some of the time and fluctuated much more from year to year than did the robbery rate. It cannot be inferred from the strong negative relationship between the robbery rate and the arrest/offense ratio that police aggressiveness deters robberies. More studies are needed to determine whether aggressive policing deters crime. Statistical data and over 10 references are included. A list of data sources is appended.

Date Published: January 1, 1981