The federal student loan program has been criticized for not adjusting interest rates according to the riskiness of factors that are under students' control, such as choice of academic major. Critics have contended that this lack of risk-based pricing contributes to inefficiency and misallocation of resources in higher education, and lower productivity in the labor market. However, recent research indicates that while high levels of student loan debt, coupled with high default rates, present a number of challenges for individual student loan borrowers and for the federal government (which must cover the defaults through taxes), they do not necessarily place a substantial burden on society at large.