Quantitative studies
Researcher examines the effect of an IV on a DV, but lacks full experimental control, especially due to the lack of random assignment.
Instead of the researcher creating groups, participants are categorized based on pre-existing traits outside of the experimenter’s control which act as the IV, and researchers then study their effects on a DV.
Useful for studying "real-world" scenarios
Harder to prove that the IV caused the effect.
It cannot definitively prove causation due to potential underlying group differences.
Quasi-experiments test a hypothesis with the application of inferential statistics to quantified data
Attempts to control extraneous variables to help ensure the IV has an effect on the DV.
Used when it is unethical or impossible to randomly assign participants to a condition.
Researchers cannot be sure that the groups are equivalent in all other characteristics, cause-effect inferences therefore cannot be made