Friday, August 14, 2015

Statistics are like bikinis:

 Statistics are like bikinis: what they reveal is interesting, but what they conceal is vital.

There is a study that states there are more police officers dying from gunfire from 1996 to 2010 in states with higher gun ownership rates. I want to fact check this article, so let's get started. The article claims:

Alabama, Alaska, Arkansas, Mississippi and Montana were the states with the highest rates of both gun ownership and for law enforcement killings. Connecticut, Massachusetts, New Jersey, New York and Rhode Island had the lowest per-capita rate for both.

I will be using the "Officer down memorial page" to list officer deaths.

There have been 29 New York officers killed by gunfire and 3 by accidental gunfire during those years.
4 in Connecticut. One of those four was shot by another cop, who was off duty and illegally hunting at the time.
5 in Massachusetts. One of them was shot in 1988, and died in 2001.
11 in New Jersey. One of them was killed while off duty and working as a security guard. 2 other cops had their cause of death listed as gunfire (accidental) because they shot themselves by accident while performing maintenance on their own weapons without unloading them.
In Rhode Island, 1 officer was killed by gunfire. 2 others were killed by accidental gunfire.

In those same years, there were 3 officers killed in Montana.
7 in Alaska
22 in Alabama
12 in Arkansas
20 in Mississippi

Population figures were obtained from the US Census Bureau. It is impossible to track population at the time of each murder, so we will use the less accurate method of simply using the 2000 figures, which would be the Census year closest to the halfway point of the period. We must use the geeral population of each state, rather than the number of police officers, because there are no available, reliable figures to show the number of law enforcement officers in a given state.

The rate of death of police officers per 1,000,000 residents in each state:

New York: 1.76
Connecticutt: 1.21
Massachusetts: 0.80
New Jersey: 1.58
Rhode Island: 3.00

So let's look now at the states that they claimed had high gun ownership rates:
Montana: 3.00
Alaska: 10.71
Alabama: 4.88
Arkansas: 4.61
Mississippi: 7.14

So what does this mean? Does it mean that they are correct, that higher gun ownership rates means more police deaths? Not exactly. There is a bit of subterfuge here. By cherry picking the states that have small populations, the death rates look much higher than they really are. For example: the rate of police killed by traffic accidents is also higher in these states. For example, the rate of police officer death was 3.57 in Mississippi, and 0.939 in New York.

TO make the comparison more fair, let's look at Florida. Florida has the highest number of concealed weapons permits in the US, with over 1.3 million people legally carrying concealed weapons.

Florida had 38 law enforcement officers killed by gunfire during the period. This means that there is an officer death rate of 2.5 per one million residents. Washington, DC, where guns were illegal for all but two years of the period, and where there were almost NO guns legally owned during that period, lost 6 officers, for a rate of 11.47. Washington DC has a population approximately equal to that of Alaska.

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