What type of research involves random assignment to groups to test hypotheses?

Experimental research is characterized by the random assignment of participants to different groups, which is a fundamental aspect of the scientific method used to test hypotheses. This design allows researchers to isolate the effect of an independent variable on a dependent variable, thereby establishing cause-and-effect relationships more effectively.

In experimental research, control groups and experimental groups are formed through random assignment to minimize biases and ensure that each participant has an equal chance of being placed in any condition. This process helps to balance out known and unknown variables that could influence the results, making the findings more reliable.

In contrast, metacognitive research focuses on individuals' understanding and awareness of their own thinking processes rather than manipulating variables. Quasi-experimental research lacks the same level of control as true experimental designs, often using pre-existing groups that cannot be randomly assigned, which can introduce confounding variables. Case study research provides an in-depth examination of an individual or small group without random assignment, focusing on rich qualitative data rather than establishing causal relationships.

Overall, the distinctive use of random assignment in experimental research lends it the rigor necessary for hypothesis testing, ensuring that the conclusions drawn from the study are more robust and credible.