Schools that closed Wednesday due to dangerously cold wind chills got their fair share of dings from students and parents. For the record, so did schools that closed.

But did either decision hurt student learning?

A study published last year by researchers from Harvard University might shed some light on the question.

That study, conducted at the behest of the Massachusetts Department of Education, found that keeping schools open during a storm is more detrimental to learning than a school closure.

Joshua Goodman, an assistant professor in Harvard's John F. Kennedy School of Government, looked at student data from 2003 to 2010 and discovered that snow days level the playing field in a sense. When some students are at school and some decide to stay home, that makes a difference, and not for the better.

"With slack time in the schedule, the time lost to closure can be regained," Goodman wrote. "Student absences, however, force teachers to expend time getting students on the same page as their classmates."

Goodman theorized that one reason closures are less detrimental is because schools typically plan for them and can tack on extra days in the schedule. They do not, however, make up days for other student absences.

Metro-area schools that opened Wednesday saw big spikes in absences, which were excused in most cases.

St. Paul Public Schools, for example, had only about half of its students show up for school. Schools in Farmington saw a similar number.

Other suburban schools experienced a range of 10 to 20 decline in attendance. Many school administrators reported that attendance was down earlier in the week due to student illnesses including the flu.

Students leaving Central High School in St. Paul on Wednesday. Photo by Aaron Lavinsky