Wednesday, March 11, 2009

Unanswered 9-1-1 Calls Explained

I received an email from a reporter recently, inquiring about my estimate of 500 police emergency calls to the 9-1-1 system that go unanswered every day. As I was typing my response, I realized that I should have already posted something on this blog to explain that number. With apologies for the delay, I present it now.

Before going into detail, I should mention that the Detroit Police Department has been unwilling to produce any official information about how many calls for police service go unresponded to (i.e., "drop off the board"). Therefore, relying on an estimate is the best that I or anyone else can could do.

Here's how I derived at the 500 calls per day figure.

A lieutenant from the Detroit Police Department attended a meeting of the Warrendale Community Organization a few months ago. During a question and answer period with its membership, he said that the Northwest District currently has an average of 40-45 9-1-1 calls go unresponded to each shift. I talked with other officers in the Northwest District who said that number is fairly accurate.

There are 3 shifts each day. 40-45 (number of unresponded calls) x 3 (number of shifts) = 120-135 calls that are presumably dropping off the board each day, just within the Northwest District.

The Northwest District is one of six police districts. 120 (lower end of that spectrum) x 6 (number of districts) = 720 calls that are presumably going without a proper response on a citywide basis each day.

Since I'm only using an estimate, as opposed to official results, I added a margin of error for sampling and assumed that the true number is only 70% of that number. 720 x 70% = 504

I, of course, rounded the 504 number down to an even 500 for the estimated average number of calls dropping off the board each day.

All of this, of course, is only an estimate that is based largely on deductive reasoning. It is possible that the true number of calls that go unresponded to is lower. However, because I was fairly conservative in my calculations, it is far more likely that the true number is actually higher.

If the Detroit Police Department ever releases any figures that put this number differently then I will post a correction. Until that happens, or until someone can show me a better estimate, I will continue using my 500 calls per day estimate.

As a related note, I should add that the Warrendale Community Organization called on the Detroit Police Department to report its 9-1-1 statistics last October. They asked the Department to report:
  • Number of police calls going into the 9-1-1 system;
  • Number of such calls that resulted in an officer showing up; and
  • Average response time for said calls.
Having that data not only enables bloggers like me to make arguments based on solid data instead of estimates, it enables everyone else to answer questions like: are things getting better or worse?

The Department, unfortunately, chose not to do so.
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