NONEXPERIMENTAL DESIGNS AND PROGRAM-EVALUATION

Sometimes implementing evaluation designs that involve random assignme nt or strong nonrandomized comparison group designs is not feasible, W hen this is the case, several other types of comparisons may offer cre dible, though not conclusive, evidence on program effects. This articl e describes three approaches-comparisons of the outcomes of the treatm ent group with a national sample, comparisons of the outcomes of progr am participants and nonparticipants, and dose-response analyses-and il lustrates their use in the evaluation of the School-Based Adolescent H ealth Care Program. The findings suggest that if outcomes are measured before and after the intervention, comparisons of the treatment group outcomes to outcomes for a national sample may provide valid estimate s of program effects. The other two types of comparisons produced impl ausible and unstable estimates of program effects, Because of the sele ction bias inherent in these two methods, researchers cannot count on being able to produce plausible estimates of program effects with such comparisons.