Santa Rosa Police Department
“I hope this goes better than last time,” thought Manuel Lopez as he pictured walking into the city council’s chambers next week. Manuel is the assistant chief of police in Santa Rosa, NM and, each September, he has to provide the city council with a report on the effectiveness of the city’s police force. This report immediately precedes the council’s discussion of the police department’s budget. So Manuel often feels like a tightrope artist trying to find the right balance in his presentation to both convince the council that the department is being run well and also persuade them to increase the department’s budget for new officers.
The city of Santa Rosa has a total of 19 police officers assigned to 5 precincts. Currently, precinct A has 3 officers assigned to it while the others each have 4 officers. One of the town council’s primary concerns each year is the amount of time it takes for an officer to begin responding when a 911 emergency call is received. Unfortunately, the city’s information system does not track this data exactly, but it does keep track of the number of calls received in each precinct each hour and the amount of time that elapses between when an officer first begins responding to a call and the time he or she reports being available again to respond to other calls (this is also known as the service time for each call).
A student intern from a local university worked for Manuel last summer and collected data shown in the file named SRPD_CallData.xlsx. One of the sheets in this workbook (Calls per Hour) shows the number of 911 calls received during 500 randomly chosen hours of operation in each precinct. Another sheet (Service Times) shows the service time required for each of these calls.
Unfortunately, the student intern had to return to school before finishing this project. Manuel has asked you to take over the analysis.
· Analyze the data to determine the inputs into a queueing model. Do arrival rates and service times follow any known distribution?
· Assuming an M/M/S model with average arrival and service rates calculated from the data, on average, how many minutes must a 911 caller in each precinct wait before a police officer begins responding?
· Suppose Manuel wants to redistribute officers among precincts so as to reduce the maximum amount of time callers in any one precinct have to wait for a police response. What should he do and what impact would this have?
· How many additional police officers would Santa Rosa have to hire in order for the average response time in each precinct to be less than x minutes? Try out different reasonable values of x.
Memo: On behalf of Officer Lopez, write a memo (in MS-Word) to the city council summarizing the results of the above analysis. Remember, the city council does not know queueing theory. So use ordinary language. Use graphs and charts if helpful. However in an appendix (in MS-Excel) provide all the work that you did to support the memo.