1. Department of Sociology, University of Oxford, Oxford OX1 1JD, United Kingdom
2. Leverhulme Centre for Demographic Science, University of Oxford, Oxford OX1 1JD, United Kingdom
3. Nuffield College, University of Oxford, Oxford OX1 1NF, United Kingdom
4. Nuffield Department of Population Health, University of Oxford, Oxford OX3 7LF, United Kingdom