what is a reversal design in research
The major methodology of this approach is the single-case experiment, or N = 1 design. Although there are many kinds of N = 1 designs, the most common are the ABAB design and the multiple-baseline design. An ABAB design, or reversal design, allows a researcher to confirm a treatment effect by showing that behavior changes systematically with conditions of No Treatment (baseline) and Treatment.
A longitudinal design is a research study where a sample of the population is studied at intervals to examine the effects of development. In a longitudinal design, you have a group of people and you study something about them. Then you collect their contact information. After a set amount of time-be it weeks, months or years-the participants are called and asked to return. Tests are re-administered to see what changes are in the participants.