Approaches to Program Evaluation
Program evaluators can use experimental approaches or quasi-experimental approaches to program evaluation. These models have some differences. An experimental approach is more rigorous when determining whether a program had an effect or not. It has a control group (Royse et al., 2016). There is an intervention group and a control group. Participants in such studies are randomly assigned. This means that individuals are assigned to groups at random. So, every person in the target population has an equal chance to become a study participant. This helps in assuming that the two groups are equivalent when starting the study reducing the threat to the internal validity of the study (Royse et al., 2016). On the other hand, the quasi-experimental model lacks randomization. Control groups are not also always used. Sometimes non-equivalent comparison groups are used which looks like the control group in experimental design. However, random assignment is not used.
However, the evaluation models share some similarities. Both provide hard evidence on the effect of an intervention. They help in discovering a causal relationship between an action and the effect. Also, both designs have a dependent variable which allows for comparison of action and effect (Royse et al., 2016). A quasi-experimental approach is more suitable where fewer resources are available to evaluate a situation. This is considering that it is less vigorous. For example, it can be used in evaluating social programs. In such research, comparable groups are formed by real differences (Royse et al., 2016). An experimental approach can be used where enough resources are available to support rigorous research. In such a situation, the model would help determine the causal effects of a program. This includes approving if the changes are attributed to the program.
Royse, D., Thyer, B. A., & Padgett, D. K. (2016). Program evaluation: An introduction to an evidence-based approach (6th ed.). Boston, MA: Cengage.
Grinnell, R. M., Jr., Gabor, P. A., & Unrau, Y. A. (2015). Four types of evaluations. In Program evaluation for social workers. Oxford, England: Oxford University Press.