Approaches to Evaluating Welfare Reform: Lessons from Five State Demonstrations. A. BASELINE DATA

10/01/1996

Baseline data are data on characteristics and experiences of experimental (or demonstration) and control (or comparison) group members, before the intervention occurs for the experimental or demonstration group, and before the comparable follow-up period begins for the control or comparison group. Such data may be obtained either from administrative records or special data collection efforts. Baseline data are critical to nonexperimental evaluations, since they are needed to control for preexisting differences between the demonstration and comparison groups. In an experimental evaluation, random assignment ensures that the experimental and control groups are the same, on average, in their background characteristics, so controlling for background characteristics is not critical in obtaining unbiased impact estimates. However, baseline data collection merits attention in experimental evaluations for several reasons. Baseline data (1) provide a check on the integrity of random assignment, (2) are used in improving the precision of impact estimates, (3) are used to define subgroups for analysis, and (4) are critical to any nonexperimental analyses (for example, of welfare recidivism, which must be analyzed using nonexperimental methods since not all experimental and control group members leave welfare during the follow-up period). Baseline data may also be important sources of contact information for follow-up surveys. Nonetheless, there have been no explicit standards or requirements for baseline data collection in the federal waiver process.