not to use race as a surrogate for qualification measures. More work is needed to assist well-intentioned realtors (with an imperfect ability to assess qualifications) in avoiding the use of race as a surrogate for qualifications.
Since individual-level discrimination and overall-level discrimination are easily confused when discussing the utility of the audit model, the two are discussed in turn below.
Sometimes audit results are reported by audit pair (averaged over realtors and circumstances of audit visits). Audit results reported for a particular pair may be misconstrued as estimates of net or gross individual-level discrimination. However, even under extremely optimal conditions, audit results for a particular pair cannot be interpreted as estimates of individual-level discrimination. Suppose the audit coordinator is successful in matching the audit pair on all possible qualifications (that vary in distribution by race). One can expect there to be many individual characteristics that do not vary across the two racial groups (black/white), yet are used in assessing renter qualifications. These characteristics may or may not be truly indicative of one's qualifications. Moreover, since the characteristics are equivalently distributed across racial groups, their use does not constitute discrimination between racial groups. The individuals in the audit pair may not be equal on these characteristics; thus the realtor may treat the individuals in the audit pair unequally, yet no discrimination occurs. Fallibility in assessing qualifications may lead to this situation. To emphasize this observation more strongly, even if both of the members of the audit are white, it may be expected that audit results for one pair (averaged over realtors and circumstances of audit visits) would result in nonzero “estimates” of individual-level measures of discrimination.
The conclusion is that audit results presented by audit pair do not represent individual-level discrimination unless an extremely strong assumption holds. This assumption is that the auditors are matched on all qualifications and individual characteristics regardless of whether these qualifications/characteristics vary by race. This assumption appears impractical and unnecessary when the goal is to ascertain overall-level discrimination. It is difficult to see how this level of matching can be achieved in practice. Indeed, this level of matching (i.e., the test coordinator has