Many studies of single motherhood and related problems of welfare use and poverty have used data from the Panel Study of Income Dynamics (PSID). Unfortunately, the PSID’s Family Unit (FU) Head definition omits subfamily single mothers not observed to leave their household of origin. Resulting biases in terms of the age, race, welfare use, and poverty status are estimated in the present study by using the 1968-85 PSID Relationship File. Substantial undercounts of single mothers in the younger ages and some overcounts at older ages are found, especially for black mothers.

Michael S. Rendall is an assistant professor in the Department of Policy Analysis and Management at Cornell University. Partial support was received from USDA Hatch Grant 322-6414 and a Cornell University Life Course Center Innovative Research Grant. Relationship-File single-mother coding was done in collaboration with Robert Moffitt, under NICHD Grant 401-HD27248-03. Research assistance from Raisa Bahchieva, Jinxu Fu, Marlene Lee, and Sara Rahman is gratefully acknowledged, as is Sandra Hofferth’s alerting the author to the development of the PSID Relationship File, and Martha Hill and other Survey Research Center staff’s valuable assistance in the use of this file. Helpful comments on an earlier version, presented at the 1995 Population Association of America conference, were received from Robert Hutchens, Marlene Lee, and Robert Moffitt. The data used in this article can be obtained November 1997 through December 2000 from Michael Rendall, 120 MVR Hall, Cornell University. Ithaca, NY 14853-4401.