Compare methods

	Occupational Gender Segregation Index	Glass Ceiling Index
Field	Gender Studies	Gender Studies
Family	Process / pipeline	Process / pipeline
Year of origin	1955	2001
Originator	Otis Dudley Duncan & Beverly Duncan	David Cotter, Joan Hermsen, Seth Ovadia & Reeve Vanneman
Type	Distributional segregation index	Distributional gender-gap criterion / index
Seminal source	Duncan, O. D., & Duncan, B. (1955). A methodological analysis of segregation indexes. American Sociological Review, 20(2), 210–217.	Cotter, D. A., Hermsen, J. M., Ovadia, S., & Vanneman, R. (2001). The glass ceiling effect. Social Forces, 80(2), 655–681.
Aliases	Duncan Dissimilarity Index, Index of Dissimilarity, Sex Segregation Index	Glass Ceiling Measure, Glass-Ceiling Effect Index, Glass Ceiling Coefficient
Related	4	4
Summary	Occupational gender segregation indices measure how unevenly women and men are distributed across occupations. The most widely used is the Duncan and Duncan index of dissimilarity, introduced in 1955, which gives the share of women (or men) who would have to change occupations for the two distributions to match. Together with margin-free alternatives and decompositions into horizontal and vertical components, these indices are the standard tools for quantifying the sex segregation of labour markets.	The glass ceiling index and related distributional measures quantify the 'glass ceiling' — the tendency for gender disadvantage to intensify toward the top of a wage distribution or organisational hierarchy. Cotter and colleagues (2001) set out formal criteria distinguishing a true ceiling from a general gap, while labour economists operationalise it as a widening female–male gap at high quantiles of earnings, and popular indices (such as The Economist's) rank countries by women's representation in senior roles, pay, and leadership.