Can anyone explain what “quasi-experimental designs” means?

You are welcome.

Thank you for the clarification!

To understand the “quasi-experimental design,” you should know the “true experimental design” first. True experimental designs use random assignment to allocate research participants to experimental and control groups. Because the two groups are equivalent, whatever extraneous factors affect the experimental group will also affect the control group. Randomized controlled trials (RCTs) (the use of a random assignment to a control group that does not receive the treatment of interest and to an experimental group that does receive the treatment of interest) are true experimental designs that provide the strongest evidence of treatment effectiveness. Quasi-experimental designs may or may not utilize an experimental or control group. However, the key feature is the lack of random assignment; therefore, they do not rule out extraneous factors.