What distinguishes quasi-experimental research from experimental research?

Quasi-experimental research is characterized primarily by its use of non-random sampling and assignment. This means that participants are not randomly allocated to different groups, which is a cornerstone of true experimental research. Without randomization, researchers face challenges in ensuring that the groups are equivalent at the study's start, making it more difficult to establish direct cause-and-effect relationships.

In quasi-experimental designs, researchers often work with naturally formed groups or cohorts and may implement interventions or treatments to observe their effects. However, because the assignment to these groups is not randomized, there can be confounding variables that influence the results, making it hard to definitively attribute any changes to the intervention itself.

The other concepts in the choices point out aspects that are typically associated with true experimental research. For instance, random assignment is essential for true experimental designs as it helps eliminate bias and increases the validity of the findings. Total control over variables is also a feature of experimental studies to ensure that extraneous factors do not affect the outcomes. The focus on qualitative analysis does not distinguish quasi-experimental from experimental research, as both may utilize quantitative or qualitative methods depending on the research questions posed.