Which research method determines cause and effect without random assignment?

Quasi-experimental research is a method that allows researchers to investigate cause-and-effect relationships without the necessity of random assignment. In this approach, researchers make comparisons between groups that have been formed for reasons other than random selection, such as pre-existing groups or characteristics. This can occur in educational settings, clinical studies, or social research where ethical or practical constraints make random assignment unfeasible.

While quasi-experimental designs can do a good job of isolating causal relationships, they are inherently limited because they do not control for all variables as thoroughly as true experiments. This lack of random assignment means that while some degree of causation can be inferred, other variables or confounding factors may still influence the outcomes.

In contrast, experimental research relies heavily on random assignment to ensure that any differences observed can be attributed more directly to the manipulation of the independent variable. Case study research typically provides in-depth insight into a single individual or group rather than establishing causal relationships. Correlational research examines the relationship between two variables but cannot establish a cause-and-effect relationship due to the absence of controlled manipulation or random assignment. Thus, quasi-experimental research stands out as a middle ground, enabling the examination of cause and effect in a practical, real-world context while recognizing its limitations