When federal workers in Washington DC. move jobs from one federal agency to another, the worker keeps her same health insurance and retirement benefits. In order to quantify the degree to which ease of transfer of benefits affects turnover, two groups of new economist Ph.D.s who accept a job in Washington, DC, are observed. The first group contains U.S. citizens. The second grc Page 4 ntains nonU.S. residents who eventually received permanent resident status after three years of work experience. By law, several government agencies cannot hire nonresidents. Among the group of US citizens, 42% changed jobs within the first three years of work while 33% changed jobs during their fourth to sixth years of work. Among the group of nonU.S. residents, 17% changed jobs in the three years before becoming a resident while 29% changed jobs in the three years after becoming a U.S. resident. Provide a differencein- differences estimator of the effect of being a U5. resident/citizen in Washington, DC, for PhD. economists