Glass Ceilings and Sticky Floors: A Representation Index

Recent research on glass ceilings and sticky floors has focused on the magnitude of differences between groups in the upper and lower quantile cutoffs of the conditional wage distribution. However, quantile cutoffs for different groups are only weakly informative of representation. For example, if the top decile cutoff is lower for minority than majority workers, this tells us that minority workers are under-represented in the top decile, but does not tell us the magnitude of the under-representation. In this paper, we propose a direct measure of the representation of a population subgroup, which we define as the proportion of group members whose earnings lie below (or above) a population earnings quantile. Our representation index is easily generalised to condition on characteristics (such as age, education, etc). Further, it generalizes naturally to an index of the severity (or cost) of under-representation to group members, which is based on dollar-weighted representation. Both representation and severity indices are easily calculated via existing regression techniques. We illustrate the approach using Canadian earnings data.