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The state and local police department are trying to analyze crime rates so they can shift their patrols from decreasing-rate areas to areas where rates are increasing. The city and county have been geographically segmented into areas containing 5,000 residences. The police recognize that not all crimes and offenses are reported: people do not want to become involved, consider the offenses too small to report, are too embarrassed to make a police report, or do not take the time, among other reasons. Every month, because of this, the police are contacting by phone a random sample of 1,000 of the 5,000 residences for data on crime. (Respondents are guaranteed anonymity.) Here are the date collected for the past 12 months for one area:
Month Crime Incidence Sample Size
January 7 1000
February 9 1000
March 7 1000
April 7 1000
May 7 1000
June 9 1000
July 7 1000
August 10 1000
September 8 1000
October 11 1000
November 10 1000
December 8 1000

(see chart in attached file)

Construct a p-chart for 95 percent confidence (1.96) and plot each of the months. If the next three months show crime incidence in this area as:

January = 10 (out of 1,000 sampled)
February = 12 (out of 1,000 sampled)
March = 11 (out of 1,000 sampled)

What comments can you make regarding the crime rate?


Solution Summary

Constructs a p-chart for 95 percent confidence and plots the data.