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Violent Crime: Is Ypsi up or down from the 70s? (The data suggest down.)

With 3 days left to the election, Ypsilanti’s claws are out over on The Facebook, with one resident’s question of how conflicts of interest are defined and dealt with diverging into an argument about whether or not Ypsi is better today than in the ’70s.  (“Are you better off than 4 years ago?” is for the amateurs in Washington–this town prefers to argue in 40-year increments.)

A sample, redacted for neighborliness:

Ypsi: shouting about the '70s

Ypsi: shouting about the ’70s

At least one of these points of contention is fairly easily tackled.  “We had less violent crime [in 1979 than today]”–oh?

The FBI’s Uniform Crime Reporting database has its problems and needs heavy caveating (as they themselves explain), but it has its uses, and comparing trends over time is pretty fair.  They provide breakdowns of violent and property crimes, as well as crime rates in crimes-per-100,000-residents.  For local units, they only go back as far as 1985; for states they go to 1960, but that’s probably good enough for our purposes.  I pulled the “Violent Crime Rate” stat for Ypsi for 1985-2012 (most recent available) for same time period for Ann Arbor (for college town and local comparison), and for the 1960-2012 period for Michigan. (I used “rates” rather than total numbers to control for population change over time.) I then normalized it all to show relative trends over time–for each of these communities, how did past crime rates compare to today’s crime rates?  Graph as so:

A2, Ypsi, Michigan violent crime rates over time, normalized to 2012 violent crime rate = 1.

A2, Ypsi, Michigan violent crime rates over time, normalized to 2012 violent crime rate = 1.


It’s pretty clear from this that Ypsilanti, Ann Arbor, and Michigan all have  lower violent crime rates today (well, 2012) than they did in 1985–Ypsi’s current rate is half what it was 30 years ago, and Ann Arbor’s 1/3.  Also, both of those communities track the overall Michigan rate in broad strokes, though more exaggerated and spikier (because of the smaller samples): if we assume that tracking of state trends extends further back, we can estimate that Ypsi’s violent crime rate throughout the 70s was 50% or so higher than in 2012.

My conclusion: at least in violent crime rates, Ypsi’s clearly a lot better off than it was in the ’80s and ’90s, and probably significantly better off than it was in the ’70s.

EDIT 3 Nov. 2014: Okay, so presenting things as ratios of present (2012) rates seems to have confused people, with multiple people on Facebook taking this to mean A2’s violent crime rates are or have been higher than Ypsi’s.  That’s not the case– for most of the 1985-2012 time period, the total (population adjusted) violent crime rate in Ypsi has been 3x Ann Arbor’s, or more.  What the graph above shows is relative rate of change: Ann Arbor’s crime rate has dropped faster than Ypsilanti’s, and Ypsi’s has dropped faster than Michigan or national averages, over the past 30 years.

Here’s another version of the graph that may (or may not!) clarify that, using 1985 as the “100% point.”  The intent in presenting some year as a baseline / 100% point was to focus on change over time, in this case to address the concern that “Ypsi’s crime has dropped [only] because the national crime rate has dropped,” to show, nope, Ypsi’s crime rate is falling faster than national or state trends alone would suggest.