A class of research designs in which program (or treatment) and comparison groups are selected non randomly but in which some controls are introduced to minimize threats to the validity of conclusions [..]

An experiment in which participants are assigned to either control groups or experimental groups in a non-random manner.

An impact evaluation design used when an experimental design is not feasible because the evaluators are not able to control assignment to experimental groups. Quasi-experimental designs use statistical techniques to create treatment and control groups that are as close as possible to identical in all respects before the application of the intervent [..]