Question

Contrast experimental with quasi-experimental methods; generally speaking, which methods are most useful?

Answer 1

Both experimental and quasi-experimental methods study by establishing a causal claim, by investigating the effect of particular treatment on a group, and by involving the use experimental group and a control group. The difference between the experimental study and a quasi-experimental study is that:

• In experimental method of study, the hypothetical counterfactuals are generated by random assignment of units in experimental and control groups.
• In quasi-experimental method of study, the hypothetical counterfactuals do not involve a random assignment of units for experiment and control group, rather, it uses the method that compares the experimental groups with groups that already exists, using various statistical designs and controls.

Both methods have their own limitations, quasi-experimental method is useful when random assignment of units are not possible as in educational field, it gives a more naturalistic approach for studies, it also decreases ethical concerns of the experimental study method. But, it lacks generalization with larger population that the experimental study method allows, also, it fails to control the intervening variables as the experimental study method, and hence, the internal validity is reduced in this method.