24. We use monthly unemployment rates and quarterly GDP for the SIPP analysis, since the SIPP provides monthly data, and yearly unemployment rates and yearly GDP for the PSID, since the PSID provides only yearly data.
25. The early release PSID data are preliminary and should be viewed as such. Also, the early release files do not include all information that is available in the final release files. For example, hours of work and state of residence are not available in the early release files. We impute values for these missing data using variable means from final release years and include a dummy variable for the early release years in our analysis. Similarly, we impute mean values for lagged variables where necessary.
26. A long-term cohabitor is an individual who has been observed in the PSID household for one or more consecutive years.
27. Citro and Michael (1995) p.397.
28. Rank and Hirschl (1999a) do, however, look at the “near-poor”—those at 125% of the poverty threshold, offering results comparable to those calculated by Bane and Ellwood and Stevens.
29. The economy was expanding from November 1982 to July 1990 (NBER 2001).
30. US Census Bureau 2000.
31. Due to the large size of the 1996 SIPP person-month entry sample, we limit the sample to the 1997-2000 time period (dropping observations for 1996 and the first quarter of 1997).
32. The National Research Council recommends that the official poverty measure continue to use families and unrelated individuals as the unit of analysis, but that the definition of “family” be broadened to include cohabiting couples (Citro and Michael 1995, p. 13).
33. Eller and Naifeh also examine annual poverty with the SIPP. They both calculate annual poverty by summing the family’s monthly income over the entire year and comparing it to the sum of the family’s monthly poverty thresholds. An advantage of this calculation is that it can account for changes in family composition throughout the year.