But lead researcher Amelia Arria said her team accounted for a range of other factors, including students' drinking and other drug use; involvement in sports and other extracurricular activities, and psychological factors such as depression.
They also measured some personality traits, like the tendency to act impulsively to seek "sensation," said Arria, an associate professor of behavioral and community health at the University of Maryland School of Public Health.
"We think that skipping-class variable is an important finding," Arria
Besides the obvious effect that would have on grades, it may reflect a broader attitude among college students who regularly smoke pot, said Arria
"We think they may be less engaged in college life, and may not be taking advantage of all the opportunities it presents," she
, the findings suggest that college academic help centers should be aware that there's a connection between pot use and student performance.
"When students go to an academic assistance office, rarely does anyone ask them about alcohol or drug use," Arria
Simply asking students about it might be enough to raise their awareness, she
"Students often see marijuana as benign," Arria
"But if you ask them questions like, 'How often are you smoking marijuana, drinking, partying?' - that alone may help them be more self-reflective and make better choices."
Parents, too, should be aware of the connection between marijuana and skipped classes, Arria
said: "Parents need to know that their investment in college could be compromised by marijuana use."
also suggested that policymakers keep it in mind.
"They may want to put academic consequences on the list of things to consider when they're deciding whether to make marijuana more available," Arria