Girls have been doing better than boys in school for as long as they've been required to go.

New research published this week in the American Psychological Association's journal analyzed more than 500 data sets, both published and unpublished, on gender differences and academic achievement dating back 100 years. The two researchers, both from the University of New Brunswick, found a consistent pattern: girls have been getting better grades than boys since at least 1914 — before education was universal and compulsory in the United States. (The last state to pass a compulsory attendance law was Mississippi, in 1918.)

In many cases, the effects were small. But no study found that boys were getting better grades, and the sheer consistency makes the results important, the researchers wrote.

The gender gap has traditionally been larger in language classes. But even in math and science, teachers have been handing out better grades to girls for a century.

The researchers say the findings should cast doubt on whether boys' education is in "crisis" because girls are getting better grades in middle school — a conclusion that the think tank Third Way drew in a report this week that found girls were doing much better than boys in the eighth grade.

"Boys have been lagging for a long time and... this is a fairly stable phenomenon," the researchers wrote. "Accordingly, it might be more appropriate to claim that the boy crisis has been a long-standing issue."