Fr. Dominic, the bread monk, demonstrates how to tell if a loaf is fully baked using three different methods: baking time, gently tapping the crust of the loaf, and using a thermometer. Transcript: Hi, I'm Father Dominic the Bread Monk, author of How to Be a Breadhead and this is a Breadhead Minute.
The difference is that in a quasi-experiment the criterion for assignment is selected by the researcher, while in a natural experiment the assignment occurs 'naturally,' without the researcher's intervention. Quasi experiments have outcome measures, treatments, and experimental units, but do not use random assignment.
A type of quasi-experimental design that is generally better than either the nonequivalent groups design or the pretest-posttest design is one that combines elements of both. There is a treatment group that is given a pretest, receives a treatment, and then is given a posttest. Quasi-experimental research involves the manipulation of an independent variable without the random assignment of participants to conditions or orders of conditions. 2  Among the important types are nonequivalent groups designs, pretest-posttest, and interrupted time-series designs.