What best defines a quasi-experimental design?

• A. A design that uses qualitative interviews only.
• B. A design with full randomization of participants to conditions.
• C. A purely observational study without any intervention.
• D. A design similar to experimental but without random assignment.

Answer: (D)

Quasi-experimental designs test causal ideas by including an intervention and a comparison group, but they don’t use random assignment to place participants into conditions. The lack of randomization means the groups may differ in some ways other than the treatment, so researchers must be cautious about causal conclusions, though they still attempt to infer effects. This is what makes it resemble an experimental design while not meeting its full standard. The other options don’t fit because they either involve no intervention at all (purely observational), or rely on random assignment (which would be a true experiment), or rely solely on qualitative methods without systematic manipulation.