Reinventing SSI statistics: SSA's new longitudinal file.

Supplemental Security Income (SSI) statistics have been published in the Social Security Bulletin since the program began in 1974. For the most part, these statistics have been snapshots of current caseloads. Now, a new SSI longitudinal file permits a retrospective look at past program data. It also permits us to redefine key program indicators and to produce new distributions for these data. In this article, we take a look back in time at SSI applications, caseloads, and awards, and describe how these data were obtained from the SSI administrative computer files.