Vahid is a health economist interested in the socioeconomic determinants of health. He uses Dutch administrative registers linking employment, income, healthcare and family histories, complemented by randomized experiments. His job market paper, Health Costs of Firms, uses linked employer-employee data and workers’ moves between firms to show that firms make a first-order contribution to workers’ healthcare costs: moving to a firm one standard deviation higher in the firm-effect distribution raises expected annual healthcare expenditure by 17.8%, with higher use of pain medication, disability and mortality, and no compensating wages within industries. A companion paper shows that the coefficient of mover-design event studies depends on which places people move between, not only on how different the places are, and asks when it can be read as a place-effect share.