January 7, 2013

Think of a number, then multiply by 2.6

The Herald has a story about police being arrested: 67 over 2 2/3 years.  That’s about 25 per year. The rate this year so far is a bit lower than in the previous two years, but well within the margin of error.

The Police Association says this proves we don’t need an independent complaints process, since the police already do a good job in catching their own when they stray. Of course, the figures don’t show anything of the sort, unless there is some independent reason to believe that 25/year is the number that should be arrested.   The Police Association also says that many of the arrests would have ‘not guilty’ results. This could be true, and it’s a pity that neither the Herald nor the Police Association provided any actual information on convictions.

The Herald also quotes a survey from October, purporting to show that confidence in police has fallen.  I covered this at the time. It doesn’t.

The arrest counts are not evidence one way or the other on how well the police are policed.  They are easier to obtain than relevant evidence would be, but that’s not much consolation.

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Thomas Lumley (@tslumley) is Professor of Biostatistics at the University of Auckland. His research interests include semiparametric models, survey sampling, statistical computing, foundations of statistics, and whatever methodological problems his medical collaborators come up with. He also blogs at Biased and Inefficient See all posts by Thomas Lumley »

Comments

  • avatar

    The data I was looking for is what is the rate of arrests for Police compared to non-Police. Agree conviction stats also essential to reach good conclusions.

    11 years ago

  • avatar

    I saw one statistic recently, which bears a similarity to the discussions here:

    Myth No. 7: Issuing more permits for carrying concealed handguns makes society more dangerous.

    There are more than 8 million concealed-carry permit holders in the U.S., and the number grows each year. These are people who are vetted by local law enforcement. They commit crime at a lower rate than the general population. And, by some estimates, they commit crime at a lower rate than police officers.

    ref: http://www.bloomberg.com/news/2013-01-01/debunking-nine-myths-of-the-gun-control-debate.html

    11 years ago

    • avatar
      Thomas Lumley

      Yes, that’s a good bad example: there’s not the slightest reason given to believe that these 8 million people would commit more crimes if they didn’t have concealed-carry permits, which is the conclusion being floated

      [Also, the ‘vetted by law-enforcement’ varies a lot by state. In the ‘shall issue’ states the police have no discretion, and in some of them the bar for qualifying is fairly low. ]

      11 years ago

      • avatar

        Yes, although I think there is a reason to believe some of these 8 million people would commit additional crimes if their permits were revoked. Many might just continue carrying concealed weapons!

        11 years ago