Discrimination on the basis of group membership might under certain conditions be rational behavior on the part of economic agents and might lead to efficient outcomes. Market competition would not tend to drive out such discrimination. Consider stereotypes, rough generalizations about traits of groups. If a stereotype is “sufficiently” accurate, it can make sense to treat all group members the same for some purpose without investing resources in determining the actual traits possessed by individual group members. For example, if an employer seeking factory workers values steady attendance at work, and absenteeism is known to be somewhat higher among African-American youths than other youth, the employer might simply set aside all applications from African-American youth and choose workers among the remainder of the applicant pool. Discrimination that is cost-effective in this way and does not involve any misuse of available information is sometimes called statistical discrimination.  The results for people who become the objects of statistical discrimination can obviously be bad. But this does not mean that statistical discrimination violates formal equality of opportunity.  Does it?