What is the defining characteristic of a quasi-experiment?

A quasi-experiment is defined by the fact that it lacks random assignment of participants to conditions or groups. This means that while it involves comparison between groups, the groups are not formed based on random procedures. Instead, participants might be assigned to groups based on pre-existing characteristics or conditions, which creates potential for confounding variables but allows researchers to study phenomena that cannot be ethically or practically manipulated in a truly experimental manner.

This characteristic distinguishes quasi-experiments from true experiments, where random allocation is a fundamental requirement for minimizing bias and establishing cause-and-effect relationships. While quasi-experiments can provide valuable insights, they do so with a need for careful consideration of how the groups differ and the influence that these differences may have on the results.

In contrast to the correct choice, having no control over independent variables (the chosen answer) refers to whether or not researchers can influence conditions, while still comparing groups. Random allocation is indeed not present in quasi-experiments but maintaining some level of control over certain independent variables can still occur. The other options concerning qualitative data and controlled environments do not inherently differentiate quasi-experiments from other types of research designs.