earnings off welfare and that heterogeneity in general is highly correlated with those variables. Third, the Ver Ploeg study demonstrated specifically for a leavers study the importance of disaggregating the caseload by heterogeneity measures, and how variable leaver outcomes are for different groups. These studies are the first in the welfare reform literature to focus on these issues and show the value of disaggregation along these dimensions. The panel recommends that this perspective be incorporated into more welfare reform studies, both within and across states, in future research and evaluation.

Recommendation 4.5 A welfare dynamics perspective should be incorporated into more welfare reform studies, including leaver studies. In general, more disaggregation by levels of heterogeneity among leavers and stayers is needed given the importance of disaggregation for outcomes on and off welfare.


The scope, volume, and diversity of existing studies on welfare reform described in Chapter 2 is impressive. However, a large fraction of those studies, if not the majority, are not concerned with formal outcome evaluation. Many are concerned with monitoring the well-being of the low-income population or segments of it and are not aimed at estimating any of the effects or outcomes discussed in this chapter. The National Survey of America’s Families, the Devolution and Urban Change Study, the Three-City Study, and many of the studies using census and other data sets to track the progress of the low-income population are not intended to formally evaluate the effects of welfare reform but, instead, have as their primary purpose the monitoring of different welfare-affected groups.26 Although some have evaluation, neither these studies nor the many excellent implementation studies of welfare reform mentioned in Chapter 2 are reviewed here, for their goal is not formal evaluation.

There are only three major types of existing projects whose primary goal is formal evaluation. These are studies of welfare leavers; randomized experiments; and caseload and other econometric studies. Even the first of these— leaver studies—is included only for discussion purposes, for most analysts agree that they are not intended as formal evaluations, at least as presently conducted.

Leaver Studies

The most common type of welfare reform study is the welfare leaver study, which examines the outcomes of a group of welfare recipients who have left the


Some of these studies, like the Urban Change Study and Three City Study, and in certain uses, the National Survey of America’s Families, have evaluation components. However, the major contribution of these studies to date is in their monitoring function.

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