A good share of this is due to sharp increases in child-only cases, driven by program and demographic shifts. To a lesser extent, this rise was caused by the expansion of AFDC-UP to all states. These two factors explain half of the overall rise, and all of the unexplained rise in AFDC caseloads. These variables appear to have increased eligibility among the core AFDC population in the early 1990s during the economic slowdown. Take-up rates also increased during this time period, but not by a large amount.
Most research tries to estimate the relative importance of the first two.
The research suggests that all else equal, as welfare programs become more generous and easier to get caseloads increase. Caseload changes are also greater when two or more of these four factors provide similar incentives for people to alter their behavior. For example, recent declines in AFDC and the FSP caseloads appear to be the result of the combined effect of the strong U.S. economy and policy changes that made work more available and more attractive compared to welfare. Similarly, program interactions are important. When programs provide opposing incentives, they reduce the behavioral response to either incentive, and when programs provide similar incentives, the behavioral response is greater than if only one program provided the incentive.