What is a quasi-experimental design?

A quasi-experimental design is characterized by the absence of random assignment to treatment or control groups, yet it still aims to establish a causal relationship by comparing groups that are exposed to different interventions or treatments. This approach is particularly useful when random assignment is not feasible due to ethical or practical considerations, allowing researchers to study the effects of interventions in real-world settings.

In this design, the comparison is typically made between a treatment group that receives the intervention and a control group that does not, thereby enabling the evaluation of the treatment's effectiveness. The key aspect is that while the groups may not be randomly assigned, they still exist, offering a framework for assessing outcomes in a structured manner.

This design is valuable in contexts like educational research or public health studies, where randomization may be difficult to implement. It provides insights despite the potential limitations regarding the internal validity that random assignment usually addresses. Understanding quasi-experimental designs is fundamental in research contexts where controlled experiments cannot be conducted, thereby contributing significantly to the field of program evaluation.