Three researchers who investigated the school performance of 12,355 students found no compelling evidence that employment affects grades.
John Warren, Paul Le Pore and Robert Mare concluded that it was invariably school performance that determined the number of hours they could work, rather than the other way round. Perhaps surprisingly, they also found that students who did no part-time work had lower school grades than those who worked between 1 and 15 hours a week.
"The overall relationship between employment and grades is far more complicated than has been acknowledged in previous research," the researchers said.
"Students and parents are apparently making decisions about how much students should work based in part on their grades."
Contact John Warren, University of Wisconsin 8128, Social Science Building 1180, Observatory Dr, Madison, WI 53706.