Why are quasiexperimental designs used more often than exper

Why are quasi-experimental designs used more often than experimental designs?

Solution

Quasi-experiments are subject to concerns regarding internal validity, because the treatment and control groups may not be comparable at baseline. With random assignment, study participants have the same chance of being assigned to the intervention group or the comparison group. As a result, differences between groups on both observed and unobserved characteristics would be due to chance, rather than to a systematic factor related to treatment (e.g., illness severity).

Random assignments of subjects helps control for participant differences, one of the main sources of threats to internal validity of a research study