Using employment concentration and commuting patterns to measure gender differences in job opportunities

Women tend to both commute shorter distances and earn lower wages. While this relationship is often assumed causal, empirical evidence on the mechanisms is lacking. Theory suggests mobile workers are likely to command higher wages, in part because they have access to more employers. We show how information on employment concentration and commuting patterns can be linked to build an index of labour market opportunities, using linked administrative and household survey data from the UK. While labour markets are porous, commonly used measures of employment concentration require well-defined geographical boundaries. We overcome this problem by combining employment concentration indices calculated using areas of different size, using the individual commuting costs as weights. We find that women have higher commuting costs and, as a result, their labour markets are smaller and more concentrated.