Which of the following scenarios could be a quasi-experimental approach?

A quasi-experimental approach is characterized by the use of intact groups or non-random assignment to conditions when examining the effect of an intervention or treatment. In the scenario described, comparing performance before and after a program without randomizing participants aligns with the principles of quasi-experimental design. This setup allows researchers to assess the impact of the program on performance while acknowledging that the participants were not randomly assigned, which is a key feature of quasi-experimental designs.

In contrast, the other scenarios represent different methodologies. Randomly assigning participants to groups is a hallmark of true experimental designs, which aim to establish causal relationships by controlling for confounding variables through randomization. Using a placebo in a drug study is also typical of a true experiment, as it typically involves random assignment and controlled conditions to isolate the effects of the treatment. Conducting purely observational research does not involve any intervention or manipulation, which is not aligned with quasi-experimental designs, where some form of intervention is implied but without the structure of random assignment.