An unidentified woman cries at a memorial for a victim of the 2002 D.C. sniper shootings.Reuters/The Atlantic

When the "D.C. Sniper" John Allen Muhammad and his then-teenage accomplice Lee Boyd Malvo went on a three-week shooting spree back in 2002, their bloody rampage did more than leave a trail of victims and spread panic throughout the capital region.

The Beltway sniper attacks also hurt math and reading scores at elementary and middle schools in Virginia that were in close proximity to the shootings, according to a new study published by the National Bureau of Economic Research. What’s more, the schools where performance worsened the most were those serving the largest populations of disadvantaged students.

The overall declines experienced at nearby campuses between the years before and after the incident were significantly greater than those at schools farther away, according to the paper, which is titled "The Effect of Community Traumatic Events on Student Achievement: Evidence from the Beltway Sniper Attacks." Seth Gershenson and Erdal Tekin, professors and researchers at American University’s School of Public Affairs, authored the paper, which uses the Beltway attacks as a case study to explore the impact of traumatic community violence on kids’ academic performance.

On average, test scores for schools within a few miles of the shootings, which left 10 people dead and three injured, declined by as much as 9 percent between 2002 and 2003, according to the study's calculations. (The study consulted schools' composite scores on standardized third- and fifth-grade math and reading assessments and calculated an estimated range for the declines; the drop in test scores could've averaged as low as 5 percent, according to the most-conservative calculation.) Notably, the negative effects were more pronounced among schools serving primarily poor and black populations, according to the researchers, who in part attributed the augmented impact on disadvantaged students to the limitations faced by lower-income parents in helping their children cope after a tragedy.

But ultimately, the researchers add, the negative effects of the shootings appeared to be "relatively short-lived"—a finding they described as "comforting."

Of course, any concern over a temporary dip in scores on a standardized test wanes in comparison to the emotional trauma that ensued after the wanton slayings in the Beltway region over the course of less than a month. Indeed, the purpose of the study isn’t to count poor test scores as anywhere near as devastating as the carnage. Rather, it’s meant to elucidate the impact that mass-casualty incidents have on student learning, particularly when such events unfold within the vicinity of American schools. While an abundance of research explores the correlation between between childhood exposure to traumatic events and psychological well-being, the study, according to Gershenson and Tekin, represents the "first comprehensive analysis of the impact of community-wide random shootings on student achievement."

Against the backdrop of what is described as an uptick in "active-shooter" incidents, massacres, and terrorist attacks in recent years, the researchers say their paper is meant to serve as a reference point for policymakers as they judge public schools’ performance under accountability frameworks such as No Child Left Behind. Under No Child Left Behind—which was signed into law just months before the Beltway sniper attacks and remains in effect to this day—schools face sanctions that range from being put on a watch list to being replaced by charters if they fail to fulfill benchmarks based on test scores and other metrics; these benchmarks are known as "adequate yearly progress," or AYP.

Though the study suggests that, overall, the sniper attacks only mildly affected schools’ AYP-based rankings (an overall drop of 2 percent at most), separating out schools serving majority black and low-income student populations reveals that the AYP scores of these campuses took a much bigger hit: reductions as large as 20 percent and 44 percent to the elementary and middle schools’ scores, respectively. (The researchers calculated conservative estimates for elementary and middle schools at 7 percent and 18 percent, respectively.)

"It is important that state and federal consequential K-12 accountability policies recognize the impacts that community traumatic events can have on the student test scores that determine sanctions, as failing to do so might expand existing inequities between schools," the study states. After all, schools that fail to meet AYP can be subject to strict stipulations attached to their Title I funding, which is money earmarked for low-income kids. The study suggests that local and state education systems provide additional resources and support to campuses and surrounding communities recover after a tragedy.    

The sniper report already has its skeptics, drawing criticism from at least one former school administrator who has experienced firsthand how violence can affect a school. That administrator, Bill Bond, coincidentally, served as a safety consultant for the public schools in Montgomery County, Maryland, just a couple of months prior to the sniper attacks. The attacks claimed six victims in the county, including four on a single day.

"I think that I would disagree with their premise that you’ve got this academic slip so we need to throw money at it," said Bond, who’s now a school-safety expert for the National Association of Secondary School Principals. Bond served as principal of Heath High School in Paducah, Kentucky, when a freshman opened fire on a prayer group in 1997, killing three students and wounding five more. "I know there’s going to be an academic setback … But after a tragedy, your emphases shift to the kids if you’re going to be successful long-term.

"It has to completely shift to being supportive and letting the chips fall where they may as far as the test goes," he continued.

The most important task faced by school leaders after a traumatic incident is to build trust with families and ensure that parents do what they can to keep their children calm, according to Bond. "I think the resources are absolutely immaterial," he said. "It’s the drama that parents inject into the situation that makes the difference, not the resources."

Bond said that a focus on academic achievement should be secondary, that the biggest priority is providing extra support for the people involved: "You have extra security, you have extra teachers," he said. "For example, one of the greatest needs after tragedy is to have the luxury of having an extra teacher—like a permanent substitute teacher—[who] can just relieve teachers when they’re having a bad moment." Money, he said, does help—but primarily when it’s invested in people rather than material school support.

Bond worked as a consultant at Montgomery’s public schools just weeks before the Beltway sniper attacks. The county's quickly ramped up its approach to school safety, he said, after the series of early morning shootings, which naturally prompted frantic parents to rush to schools to pick up their children early. The former principal attributed much of the post-incident performance declines to the emotional fallout experienced by kids’ families: "If you can’t stop that parent drama," he said, "it’s going to affect your school academics."

Bond also criticized the study’s suggestion that parents of lesser economic means struggle to support their kids after a tragedy as much as their more affluent counterparts do. According to the American University researchers, parenting style and the types of behaviors adopted by parents following these events—attempting to minimize the trauma by limiting their kids’ exposure to news media, for example—"can influence the extent of the harm caused to their children." Demanding work schedules or personal stresses, on the other hand, "may limit the amount of extra care and emotional support that they are able to provide to their children during these times," the report says. "Even worse, the stress experienced by parents might even lead to counterproductive behaviors, which may further fuel anxiety and fear among children."

Bond emphasized his rejection of the idea that time and money help kids cope. "To me that’s one of those things that you’re almost saying poor people don’t value their kids as much as rich people because they’re not investing as much time," he said.

Further analysis of the study also suggests that the research suffers from flaws beyond issues such as parenting style and emergency funding. One of the biggest problems with the investigation, it seems, is that it fails to sort out whether the lower test scores at schools near the attacks resulted from stress and anxiety over the incidents themselves—or from the subsequently higher rates of student absenteeism. If the latter is the case, then presumably similar outcomes would ensue after a series of snow days.

Gershenson, one of the researchers, acknowledged this limitation, writing in an email that, absent sufficient reliable data, "we can't say for sure whether student absences caused by the attacks were what led to declines in academic achievement." Instead, he said, the study speculates about the various "possible mechanisms" through which these incidents might have taken a toll on school performance. "Student absences are certainly one likely mechanism, and some anecdotal evidence suggests that this is true, but other possibilities exist as well—such as school closures, disruptions to routines, stress, teacher absences, and so on."

It’s also worth noting that the research focused exclusively on proficiency in Virginia schools even though campuses in Maryland and D.C. were in the vicinity of areas affected by the attacks. In other words, the findings don’t appear to be as "robust" as the authors make them out to be. Gershenson said data on D.C.’s public schools for their part would be "less useful" because the statistical analysis relies on having a "control group" of schools that were located more than five miles from any of the attacks, whereas the district’s schools are all concentrated in a relatively small area, too large a percentage of them within that radius.

Unfortunately, there’s no shortage of similar incidents in recent history to analyze in an effort to advance the research on mass trauma and school performance. According to one FBI study that was cited by the researchers, the country has experienced 160 active-shooter incidents between 2000 and 2013—incidents that left 486 people dead and another 557 wounded. An average of 6.4 active-shooter events occurred annually between the years 2000 and 2006; that number increased to 16.4 annually between the years 2007 and 2013.

These statistics show that calculating the impact of mass violence on test scores is a task that could be revisited for years to come.

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