Mass shootings in the U.S.

Andrey Kamenov

Andrey Kamenov, Ph.D. Probability and Statistics

There are different sources of data on mass shootings in the U.S. The most important of them are mentioned in this story in the Washington Post.

We’ll use the most complete source: Mass Shootings Tracker. Despite also being the most recent addition to the list, this database seems to provide the most reliable data. As of January 2016, it had data on 500 events, where 543 people were killed and 1976 were injured. More than half of them involved exactly four victims; the number of cases where more than six people were shot is just over 10 percent.

Here’s an animated map showing all mass shootings from the archive – both the color and radius of an event here represent the total number of victims (injured or killed).

Mass shootings in the U.S. since July 2014

There’s a question that is stated in nearly every article on gun violence: does it correlate with gun ownership rate? Well, at the very least, we can give an answer regarding the number of mass shootings.

Below is a scatter plot showing gun ownership rates and the number of mass murders (per 100,000 residents) for all states and the District of Columbia (the latter is seen as an outlier on the top left). It also shows a confidence interval for a simple linear model, suggesting that there is no statistically significant relationship between the two variables.

Mass shootings and gun ownership rates

Of course, we’ve also conducted a more thorough statistical research. For that, we used a Poisson generalized linear model, only to come to the same conclusion. While the average number of mass shootings is lower in states with higher gun ownership rates, the relationship is not strong enough to be considered significant.


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About Andrey Kamenov

Andrey Kamenov

Andrey Kamenov, Ph.D. Probability and Statistics

Andrey Kamenov is a data scientist working for Advameg Inc. His background includes teaching statistics, stochastic processes and financial mathematics in Moscow State University and working for a hedge fund. His academic interests range from statistical data analysis to optimal stopping theory. Andrey also enjoys his hobbies of photography, reading and powerlifting.

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One thought on “Mass shootings in the U.S.”

  1. A more telling stat would be the incident rates in concealed carry areas vs. gun free zones.

    This slight of hand “study” is a case of not asking, or not wanting to ask the right question in fear of the conclusion.

    The second amendment protects the first amendment.

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