Correspondence studies are popular tools for assessing discrimination against minorities, for example, in the labor market. Typically, two fake "Curriculum Vitae" (CVs) are sent to multiple job openings. The CVs are equivalent except for a mark identifying the disadvantaged. While it is straightforward to establish discrimination from minorities' lower response rates, it is often unclear what its source may be. Discrimination may result as much from employers' aversion toward a minority, as from perceptions that members have lower or more dispersed abilities that are unstandardizable in a CV. We refine existing methodologies to propose a wider-scope method capable of disentangling these three sources of discrimination and establish its face validity applying it to a correspondence study aimed at assessing labor market discrimination against ex-convicts in a local market.