Understanding the new method of policing in Northfield

In today’s Northfield News: Burglaries in Northfield down by 40 percent in 2011

Northfield crime stats 2009 to 2011While calls for service are up through the end of last week, crime overall is down, most notably in the burglary category, which saw a 40 percent drop over 2010.

Deputy Police Chief Chuck Walerius believes that the reduction, along with a drop in reported crimes, is linked to a new method of policing the department instituted this year that takes into account the types of crimes being committed and the most likely trouble spots when allocating resources. Walerius said it’s not only helped to reduce crime, but help officers catch things as they unfold.

Northfield police incident mapping 4th qtr 2011Here’s a map of property crimes in Northfield in the past 90 days, as generated by Northfield’s Police Incident Mapping Application. The pushpin icons represent burglaries, thefts, vehicle thefts, and damage to property. No robberies or arsons were reported. (The crime map only displays property crimes, whereas the table above shows all types of crimes. Also, see this site on the difference between theft and burglary.)

Where are the "most likely trouble spots" that would be new?

And what might Deputy Police Chief Chuck Walerius mean when he says that the new policing method "takes into account the types of crimes being committed"?

I may be able to get him to comment here but it might be helpful to first have some discussion. Maybe I’m the only one who’s puzzled.


  1. Bruce Morlan said:

    Griff, you should not be the only one puzzling over this. To call a change from 79 incidents (2010) to 48 (2011) a decrease without noting that the 79 appears to be an outlier from a trend up since 2009 (with 42 incidents) is pure spin. Unless in 2008 the count was 125 or so, in which case the 48 in 2009 was the outlier … blah blah blah.

    Okay. the conversation around these statistics is unsustainable.

    [As an aside, this is an example of data mining (which is the old, now politically incorrect term for statistical analyses usually associated with profiling). It attempts to extract information from the data, information that used to be the province of the beat cop who knew the criminals by name, and just had to hope to catch one of them in the process of committing a crime. At a recent conference on this subject we learned that the new, less sensitive, term was “business analytics”. Too bad Northfield data is not online here (try “Dennison, MN” as the location, use the Incidence Layers drop down to select all and apply).]

    January 2, 2012
  2. Jim Haas said:

    The criminologist James Q. Wilson pointed out years ago that police will generally take credit whenever crime numbers go down (by whatever measure) but will seldom take blame when the numbers go up. Decreases are due to better policing; increases are due to a bad economy, lenient judges, crooked parole boards, the ever-present drug epidemic, family breakdown, and so forth. And comparing one year to the previous year is, as Mr. Morlan points out in comment #1, waaay too simplistic. I’m surprised Mr. Walerius fell into that trap (or would try to spring it on us). And the reporter did us all a disservice by not looking deeper into the whole business of counting crime.

    January 3, 2012
  3. Griff Wigley said:

    Bruce, thx for chiming in with your statistician and mathematician hat on.

    Jim, likewise, as the recently retired Community Corrections Director for Rice County.

    Are there specific questions that y’all would like to ask the Nfld PD about the crime stats?

    January 4, 2012
  4. Jim Haas said:

    Griff: I wouldn’t ask any questions abut crime stats themselves, since the data are (is?) readily available. I would ask more specific questions about exactly what the ‘new’ policing strategy is; when did it start; was burglary the primary target; and, most relevant, what evidence do you have that the one-year reduction is directly attributable to the new policing strategy? I’ll point out that, with few exceptions, crime (as measured by the Uniform Crime Reports) in the US, in Minnesota, in Rice County, and in Northfield has been dropping fairly steadily for over a decade.

    January 4, 2012
  5. Jim, as you note, police take credit but not blame, just as politicians take credit for good economies but not the blame for bad (except to blame the other party). Teasing out Correlation, Coincidence and Causality (the 3-Cs) statistically is more than a full time job, and it is never surprising to see people picking their favorite C when discussing policy and practice. An interesting meta-analysis by Steven Levitt (of Freakonomics fame, published in 2004, stated that

    Four factors, however, can account for virtually all of the observed decline in crime: increases in the number of police, the rising prison population, the waning crack epidemic and the legalization of abortion.

    Of these, the number of police is important as it is about the only factor a local community can address, since prisons, drugs and abortion are all controlled exogenously.

    Interestingly, after eviscerating someone who had predicted chaos in the coming decade (roughly 1995-2005), he proceeds to offer his own projections for the future (2004-). He does so after observing that “the crime decline was so unanticipated [in the 1990’s] that it was widely dismissed as temporary or illusory long after it had begun.” [emphasis added] (Sounds like global warming, eh?). Here, unanticipated must mean “not predicted by the existing models” or “predicted but not accepted as reliably so”. A cautionary tale, indeed, for we practicing statistical/analytical Cassandras.

    January 4, 2012
  6. Griff Wigley said:

    So given the drop in crime in Northfield, can the City Council make the argument that it’s possible to reduce the police force during these lean budget times?

    January 4, 2012

Leave a Reply