Stats exaggerate U.S. gun violence

Firearm homicides: Germany — 381, France — 255, Canada — 165, U.K. — 68, Australia — 65, Japan — 39 and U.S. — 11,127."

According to a preview for Michael Moore's recent film, "Bowling For Columbine" (www.bowlingforcolumbine.com), these numbers illustrate the relative amounts of gun violence in various countries. Taken at face value, these mysterious, unexplained figures seem to confirm the standard, fashionable indictment of the U.S. as an out-of-control, excessively violent nation. However, upon further inspection and comparison with the real numbers, one finds that the U.S. does indeed have a higher homicide rate than the other countries on the list, but that things are not nearly as bad as Mr. Moore's numbers seem to say.

After encountering these numbers, I was naturally skeptical, for the preview gives no source for them; it does not even say what their units are! Do they represent homicides per year? Per week? Are they normalized to control for differences in population among the various countries? These are important considerations which would profoundly influence the conclusions which can be drawn from the numbers — the latter question in particular is vital, for if one country has twice as many murders, but also twice the population of another, then the two are equally crime-ridden. It is the homicide rate, not the raw number of homicides, that should be used in a cross-country comparison.

Mr. Moore and his staff were not immediately available for comment via an email address listed on the film's website, so it is still unclear to me exactly what the numbers represent. However, what is clear is that they are highly inaccurate and unrepresentative of the true differences in the homicide rates between the listed countries.

This fact can be verified by checking official international crime statistics, which are archived on the website of Interpol, an international police organization, at www.interpol.int. The explicit link to the Interpol reports as well as copies of the calculations I am about to describe (in Excel, html and text formats) are publicly accessible at www.princeton.edu/~eharkler.

For each of countries listed in the preview for Mr. Moore's film, I looked up both the number of homicides and the population in the year 2000. I then normalized the homicide rate to homicides per 100,000 people. For example, in 2000 there were 2,770 homicides in Germany among a total population of 82,163,475. This yields 2770/ 82,163,475 * 100,000 = 3.37 homicides per 100,000 people in the year 2000. Similar calculations for each of the countries listed allow us to compare the homicide rates in the different countries and to perform a check of Mr. Moore's numbers.

According to Mr. Moore's numbers, the homicide rate in the U.S. is 30 times greater than that of Germany, and 285 times greater than that of Japan. However, based on Interpol statistics for 2000, these numbers are actually 1.64 and 5.03, respectively — a difference which is not due to technical or statistical error, but likely to a creative and narrow choice of source data on Mr. Moore's part. Most likely Mr. Moore's numbers are not actually fabricated, but rather chosen from a year in which the homicide rate in the U.S. relative to other countries was unusually high and not representative of the average over time. As the Interpol data for 2000 shows, a broader perspective might yield more sober results.

Clearly Mr. Moore is profoundly biased in favor of gun control and against Americans' 2nd amendment right to bear arms. That much is readily apparent from the film itself and can be ascertained even without doing a sanity check on his numbers. While I acknowledge that gun violence is a problem in the U.S. and other countries, I take issue with Mr. Moore's questionable methods of combating it.

Granted this is only a movie — hardly a rigorous scholarly study of gun violence. However, it is especially important that people in a position to influence public opinion, such as Mr. Moore, be careful when using numbers and statistics to make a point. Furthermore, it is important that the public and policymakers not take such numbers, and the conclusions drawn from them, at face value. Eric Harkleroad is a physics major from Overland Park, Kan. He can be reached at eharkler@princeton.edu.