ties and smaller entities administrative freedom to operate programs. The task of simply recording each of the new policies that have been legislated in each state or county, how those policies have been implemented, and how they are evolving over time has become much more difficult and will require major effort because of the variation in program rules. Reporting requirements in the 1996 Act and in the federal regulations that have followed it require the states to report some aspects of their policies on an annual basis, but far less than what is required for a comprehensive accounting of the welfare programs that are available to the poor families in each state.
A second challenge is to the nation's data infrastructure on poor and welfare populations, which must necessarily be the basis for assessing the effects of PRWORA. The extensive variation of programs across the country puts great strain on national-level data sets based on household surveys—such as those conducted by the Census Bureau and other federal statistical agencies—because the samples of the welfare-relevant and poor populations in those surveys may not be large enough to capture the effects of welfare reform. State-level data sets, both administrative and survey based, will be asked to provide new information far beyond anything they have previously needed to provide, for such data have historically been primarily used for management rather than evaluation purposes.
A third, more analytic, set of challenges is that of assessing the effect of legislation relative to other forces and trends in the economy and society. Foremost among these is the necessity to separate the effects of the improving U.S. economy and the PRWORA legislation, both of which occurred almost simultaneously. Choosing a comparison group with which to assess the effects of PRWORA is made especially difficult by this occurrence. Additionally, cross-state comparisons are complicated by the need to account for differences in economic and policy environments other than those in PRWORA-related policies. There are also challenges in assessing which of the many provisions of PRWORA have effects and which do not, for all the provisions were enacted at roughly the same time. Another part of this analytical challenge is to assess the effects of PRWORA on participation in other social welfare programs that were not substantially changed in the legislation (such as food stamps and Supplemental Security Income [SSI]).
It is in this context that the Office of the Assistant Secretary for Planning and Evaluation (ASPE) of the Department of Health and Human Services (DHHS) asked the Committee on National Statistics of the National Research Council to convene the Panel on Data and Methods for Measuring the Effects of Changes in Social Welfare Programs, using funds in a congressional appropriation to ASPE for this purpose. The same congressional appropriation provided funding to ASPE for data collection and evaluation of the effects of welfare reform on families who have left welfare, commonly called "welfare leavers." Language accompanying the appropriation requested that the new panel provide guidance