By Douglas Belkin

Researchers at Northwestern University have found one pattern in the seemingly chaotic nature of school shootings: They rise and fall with the jobless rate and other signs of economic uncertainty.

After creating a database of 25 years of school shootings, the researchers attempted to correlate shootings with economic data such as growth in GDP. But their core finding was that when the school-to-job pipeline begins to crack, more people are shot in school.

"If you stay in school, it is because, to some extent, you are buying into the idea that you will graduate, get a job and be a productive member of society," said Luis Amaral, a co-author of "Economic Insecurity and Rise in Gun Violence at U.S. Schools," was published Monday in the journal Nature Human Behaviour.

When that link is broken "there is really this feeling that you are being betrayed. You do all of these things and then you don't get the reward you expect," added Mr. Amaral, who is also the co-director of Northwestern's Institute on Complex Systems.

In the last 25 years, there have been two periods of elevated gun violence at U.S. schools: 1992-1994 -- when the shootings ticked up in high schools, and 2007-2013 when shootings rose at colleges. The researchers note that in addition to having a hard time finding a job themselves, students may be responsive to the unemployment of their parents.

In the 1992-1994 period, there were 2.8 shootings a month while the average unemployment rate was 6.9%. And between February 2007 and December 2013, the unemployment rate averaged 7.67% and there were 1.85 shootings a month, according to Adam Robert Pah, another co-author.

During the span of time separating those periods there was a lower level of school violence, with 1.02 shootings a month. The average unemployment rate for that span was 5%.

The researchers created a database of 381 of school shootings that met the following criteria: each incident involved a firearm that was discharged on a school campus and involved students or school employees as perpetrators, bystanders or victims.

In addition to unemployment, the researchers found that the foreclosure rate and consumer confidence also correlates with the rate of school shootings. "This is a generalizable phenomenon that can be robustly measured with a variety of measures of economic insecurity," the authors wrote.

Of school shootings in the study, 6.6% are connected to gangs, and the average number of fatalities per event was one. Just under 7% of all incidents involved three or more deaths. Gun violence at schools hasn't become more deadly over time, the study added.Dr. Amaral said the study points toward the "double whammy" of a lack of funding for anti-violence programs just when it is needed the most.

"When the economy is not good there is a higher likelihood of more school shootings and that's just when localities have less resources for after school programming or increased security," he said.

Write to Douglas Belkin at doug.belkin@wsj.com

(END) Dow Jones Newswires

January 30, 2017 19:04 ET (00:04 GMT)

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