as “studies that do not involve the application of treatments via random assignment of subjects. They are also called observational studies.”
This reader thought the concepts of observational study and quasi-experiment should be disentangled, i.e.
- Experiment: Randomization + treatment applied
- Observational Study: No randomization, no treatment
- Quasi-experiment: Comparison groups with no randomization, or one group with multiple pre/post measures, + treatment applied
This is not my field, but it makes sense so I thought I’d pass it along.