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The City of Anchorage uses a publicly accessible crime map, Crime Map http://crimemap.muni.org/ which can be quite useful to people moving into the city from rural areas and looking for places to live and work. Like any map, it is only as good as the information or data put into the map. As with the preparedness plans, what-me-worry-we-have-plan, it is up to all of us to ask if maps make sense.

This discussion from the LATimes, Highest crime rate in L.A.? No, just an LAPD map glitch, about their questioning is a good example. It is important to note that “the experts” have to include us, the folks who live and use such information. The mapmakers or government or “them/they” only know what they know. I have found we’re essential to our own lives and can’t pass that responsibility on to others, i.e., public involvement works.

One reason the errors were not caught earlier may be that the LAPD site retains crimes for only six months and allows viewers to see only a seven-day period at a time. The presentation makes some trends, such as the large accumulation of crimes mapped at Civic Center, more difficult to spot. The mistakes spread on the Internet, often compounding the distortion.

EveryBlock, an enterprise that specializes in pulling together local data from many sources, has been praised as a model for the future of journalism, but unlike traditional publications, the site takes no responsibility for the accuracy of its aggregated data.

But the newfound ease provided by online services can create a false sense of confidence in the computer’s matching ability. Behind the scenes, an algorithm tries to translate unruly street addresses, often drawn from handwritten forms, into the precision of decimal degrees. …

  • mapping errors could affect policy decisions.
  • Small changes in how an address is typed — for instance, “68th St.” instead of “W. 68th St.” — can put the point in the wrong neighborhood or even the wrong city. Adding or removing the name of the city or a ZIP Code can lead to differing results. Because of the way they break up the parts of an address, Google and Yahoo sometimes return different locations for addresses typed exactly the same way.
  • Mistakes could have the effect of masking real crime spikes as well as creating false ones.

I’m forwarding a copy of the LATimes article to the Anchorage Police Dept. as some of the same factors are in the Anchorage map (e.g., only a few days are available).

2009-04-07T03:49 Lt. Parker of APD writes back (thank you) that all their

police data entry systems have the required address field. Many like ours use the police department headquarters as a default for crimes not associated with a specific location. It sure looks like lots of crime is taking place at the police department on those crime maps though! I can assure you that it is only a computer glitch.

From these maps below, when would you suspect (hypothesize) people receive their monthly checks?

Anchorage map of April 1, 2009 reported crimes

Anchorage map of April 1, 2009 reported crimes

Anchorage daily crimes reported 2 April 2009

Anchorage daily crimes reported 2 April 2009


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