Friday, May 29, 2009

Arrest rates

A regular reader, Mr. Wilson, just pointed out a few minutes ago that the charts in my previous post are incongruent, in that the crime graph on the right is expressed as a rate per population, whereas the arrest graph on the left is not a rate—just the raw numbers. He is quite correct, and I had that same thought right after I posted it this morning. I knew that a graph for arrest rate would be slightly flatter. At any rate, here’s a couple of different rate graphs, Mr. Wilson. Nice catch!



Anonymous said...

Does the left graph show that old saying '90% of the crime is committed by 10% of the population'?

car54 said...


Nice charts and you have piqued my interest. While it will take some time I think I will try to generate the same information for my agency. However I do have a few questions. What are you counting as an arrest?

I also know the NIBRS and UCR are an attempt to draw some conclusion about the effectiveness of police agencies. Do you think the arrest per officer can be used to draw any conclusion about how effective a police department operates? Or are there other factors that come into play?

Tom Casady said...

car54 -

It's interesting information, but I just don't think you can draw any firm conclusion from it. There are too many factors in play. In general, I believe that when you have high arrest rates, you are basically reflecting the productivity of officers, rather than the amount of crime. A department with a streamlined process for handling misdemeanor arrests, for example, is likely to have more of those than a jurisdiction where a DWI is an all-shift ordeal.

Although I can't prove it, my sense is that our high arrest-per-officer rate here is caused by our particularly effective use of information resources, coupled with a good work ethic by our personnel.

I've never seen a department that puts as much information at officers' fingertips as ours. I've chronicled a few examples in this blog. I can't help but think that this helps. Our officers' work ethic, though, is really the key. Make a lot of traffic stops, you'll make a lot of criminal arrests. Follow-up on cases thoroughly, you'll end up actually catching more shoplifters, assault suspects, and so forth. Use good tactics, teach those to others, and we all soar.

Steve said...


Don't get me wrong, I'm not criticizing all this number crunching you do in the least. I know it has to be done, if for no other reason than to justify your requests for resources that will improve the department's performance. I'm sure it also helps fine tune your methods and focus on the issues where you can really make a difference. However, in the long run, don't you suspect that it will eventually prove what most of us (Chief's Corner readers) already know? That is, you've got to "nip it in the bud."

It starts out long before police would ever be involved. Parents need to teach their children right and wrong at an early age. They must find a way to make their children understand that bad behavior will not be tolerated. I don't care if it's through "time outs" or a belt to the behind; whatever works.

Now, I also know that with some kids, nothing works. Or, the parents don't do their job for one reason or another. Or, it only works temporarily; until the kids grow up a bit and decide for themselves what is right or wrong. That's when the police and the courts need to step in and reinforce what the parents tried to teach them earlier. And, like the parents, they cannot allow the bad behavior to continue. At this age, "time out" means jail.

There is no justification in my mind for any person to have an arrest record "as long as your arm" as it is often called. I'd say when it gets to the third knuckle, it's time to throw away the key.

I'm convinced that if parents (and when necessary, police and courts) would "nip it in the bud," we wouldn't need the additional jails that people are always crying about because crime would only be a fraction of what it is now.

Tom Casady said...

car 54-

Sorry, failed to answer your other question:

'What are you counting as an arrest'?In our vernacualr, it is any charge for a criminal misdemeanor or infraction, excluding traffic tickets. Since 90% of those arrests are misdemeanors, and since the great majority of misdemeanants are released with a citiation rather than being booked into jail, you should not confuse the number of arrests with the number of people who actually heard the jail door clank.

Also--it's charges, not persons. Some of these are multiples, and some individuals are...


Mr. Wilson said...

Thanks for the new graphs, Chief!