1. For the classic discussion of this issue, see Richard Easterlin, Birth and Fortune (Chicago: University of Chicago Press 1980).
2. See, e.g., U.S. Bureau of the Census, Table 2b, “Projected Populations Change in the United States, by Age and Sex: 2000–2050,” http://www.census.gov/ipc/www/usinterimproj/natprojtab02b.pdf.
3. National Center for Health Statistics, U.S. Department of Health and Human Services, Health, United States, 2006 (Washington, DC: U.S. Department of Health and Human Services, 2006), http://www.cdc.gov/nchs/data/hus/hus06.pdf#027.
4. John B. Shoven, “New Age Thinking: Alternative Ways of Measuring Age, Their Relationship to Labor Force Participation, Government Policies and GDP.” (working paper 13476, National ...