Analysis of nonparticipation in the SSI program.

This article addresses a range of questions about participation and nonparticipation in the supplemental security income (SSI) program with data collected by the Survey of Low-Income Aged and Disabled (SLIAD) during 1973 and 1974: (1) Can SSI's relatively modest growth be attributed to initial overestimates of the eligible population or to low rates of participation among eligibles? (2) If the latter, what factors inhibited program participation? (3) What is the relation between program participation in SSI's initial years and at the present time? (4) If the factors that initially inhibited participation have not significantly changed, what are the present implications for program policy? The first section of this article discusses the size and composition of the program's target population. Various estimates of the eligible SSI population are compared with microsimulation estimates based on SLIAD. The second section presents the theoretical and empirical framework used to analyze the factors associated with nonparticipation in SSI. The theory of nonparticipation, developed in the context of the "alternative income hypothesis," is presented in a series of propositions used to empirically verify the theory. The third section discusses the factors related to participation in the SSI program during and after the phase-in period. Subsequent response to SSI is presented in a discussion of outreach efforts and trends in program applications and program enrollments. The final section discusses the implications of the existence of an eligible nonparticipant population and what, if any, changes could be made to increase program involvement.