The Adequacy of Comparison Group Designs for Evaluations of Employment-Related Programs
通过对比实验设计（国家支持工作示范项目）与非实验设计（基于当前人口调查构建的比较组）的结果，发现非实验设计无法可靠估计就业培训项目的效果，其估计值对方法和模型敏感。
This study investigates empirically the strengths and limitations of using experimental versus nonexperimental designs for evaluating employment and training programs. The assessment involves comparing results from an experimental-design study-the National Supported Work Demonstration-with the estimated impacts of Supported Work based on analyses using comparison groups constructed from the Current Population Surveys. The results indicate that nonexperimental designs cannot be relied on to estimate the effectiveness of employment programs. Impact estimates tend to be sensitive both to the comparison group construction methodology and to the analytic model used. There is currently no way a priori to ensure that the results of comparison group studies will be valid indicators of the program impacts.