What is a quasi-experimental design?

A quasi-experimental design is characterized by its resemblance to true experimental designs but fundamentally lacks random assignment of participants to control and experimental groups. This absence of random assignment can occur due to practical or ethical reasons and often involves using predetermined groups, such as existing classes or communities, to evaluate the effects of an intervention or treatment.

This type of design is often employed in real-world settings where randomizing participants may not be feasible, allowing researchers to still make comparisons between groups. Quasi-experimental designs may include pre-existing differences between groups, making them valuable for understanding the impact of certain interventions without the strict control of a randomized approach.

The other options describe features that do not align with the nature of quasi-experimental designs. For example, a design with random assignment is a hallmark of true experimental research, while observational studies lack intervention entirely. A purely theoretical design with no practical application does not fit within the framework of experimental methodologies focused on empirical evidence.