Andrey Kamenov, Ph.D. Probability and Statistics

The deadliest shooting in U.S. history happened last year in Las Vegas. But there is much more to gun-related incidents. The Gun Violence Archive database is one of the most complete sources of data. By now, it has records of over 30,000 gun-related incidents that happened this year — and that’s excluding accidental shootings.

Is there any pattern? Or are these incidents completely random?

Here’s a plot showing the total number of incidents, day-by-day, from the start of the year.

The chart looks quite jagged. In fact, it appears that there’s a peak roughly every seven days. A simple statistical analysis is enough to see if there’s indeed a pattern:

Average number of gun violence victims each day

Here it is. All the weekdays are well within the margin of error. At the same time, significantly more incidents occur during the weekends. On any given Sunday, an average of 99 people are injured and 42 are killed. On Thursdays, the numbers are 63 and 29 respectively.

What’s more, the findings are consistent — the difference is more or less the same for every state. And it doesn’t change month-to-month, either.

Another coincidence that is worth mentioning: The Las Vegas shooting happened on a Sunday. In fact, out of 383 mass shootings (four or more victims), 47 percent happened during the weekends; this makes it 64 percent more likely that a mass shooting happens during the weekend.

Source(s):

• The Gun Violence Archive data

About 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.

Other posts by Andrey Kamenov:

• Are people living outside the metro areas cushioned against falling home prices?
• Owners prefer to build small homes outside of metro areas
• Exercise or sleep: which is more important for your health?
• Measuring health levels in the U.S.
• Where to be born in the U.S.