“Why Do Women Earn Less Than Men? Evidence from Bus and Train Operators”, Valentin Bolotnyy, Natalia Emanuel2022-02-23 (economics, personality, sociology)⁠:

Female workers earn $0.89 for each male-worker dollar even in an unionized workplace, where tasks, wages, and promotion schedules are identical for men and women by design.

Using administrative time-card data on bus and train operators [from the Massachusetts Bay Transportation Authority], we show that this earnings gap can be explained by female operators taking fewer hours of overtime and more hours of unpaid time off than male operators…Mechanically, the earnings gap in our setting can be explained by the fact that male operators take 1.3 fewer unpaid hours off work (49%) and work 1.5 more overtime hours (83%) per week than their female counterparts…Female operators, especially those with dependents, pursue schedule conventionality, predictability, and controllability more than male operators.

While reducing schedule controllability can limit the earnings gap, it can also hurt female workers and their productivity.

…When overtime is scheduled the day before or the day of the necessary shift, male operators work almost twice as many of those hours as female operators. In contrast, when overtime hours are scheduled 3 months in advance, male operators sign up for only 7% more of them than female operators. Given that the MBTA’s operators are a select group who agreed to the MBTA’s job requirement of 24/7 availability, these differences in their flexibility and in their value of time could be lower bounds for the general population.

…Second, female operators prioritize conventional and predictable schedules. As operators move up the seniority ladder and consequently have a greater pool of schedules to pick from, female operators move away from working weekends and holidays and split shifts more than do male operators.

…Female operators value time outside work and schedule predictability more than do male operators, especially when they have dependents. Female operators with dependents are considerably less likely than male operators with dependents to accept a short-notice overtime opportunity. When it comes to overtime hours worked, unmarried female operators with dependents work only 6% fewer of them than men when they are preplanned 3 months in advance but about 60% fewer of them when they are offered on short notice. Unmarried women with dependents also take the largest amount of unpaid time off with FMLA, making them the lowest earners in our setting.