In evaluation research, what distinguishes “experimental design” from other designs?

In evaluation research, experimental design is characterized primarily by its use of random assignment to groups. This approach enables researchers to create two or more groups that are statistically similar at the outset of the study, thus controlling for confounding variables that might influence the outcome. By randomly assigning participants to either a treatment group or a control group, researchers can compare the effects of an intervention or program while minimizing biases that could arise from pre-existing differences among participants.

This method allows for stronger causal inferences about the relationship between the intervention and the outcomes measured. The random assignment process ensures that any observed effects are likely attributed to the intervention itself rather than to external factors. Thus, experimental design serves as a robust method for evaluating the effectiveness of programs or treatments.