Consider the occupational variable service orientation to consumers (Hogan & Hogan, 1992). Although it might be appealing to hypothesize that conscientiousness, one of the five broad domains measured by the NEO PI-R, relates to service orientation, that hypothesis is imprecise. In fact, Costa and McCrae (1995) found that one trait within the conscientiousness domain, dutifulness, correlated .35 with service orientation, while another, achievement striving, correlated −.01 with the same criterion. Achievement striving did correlate highly with a different occupational variable, managerial potential (r = .63), but another facet of conscientiousness, order, accounted for comparatively little variance in that criterion (r = .25). We note two things about this example. First, these findings are typical: Facets within domains often have markedly different external correlates. Second, the findings do appear to support the validity of the facet scales; they make sense given the nature of the constructs being measured. Therefore, facet-level findings such as these lead to advances in understanding of psychological processes. They would not have occurred if Costa and McCrae (1995) had correlated only broad conscientiousness with the occupational variables. The precision gained by studying homogeneous constructs is fruitful.
