Many single-subject experiments appear in the Journal of Applied Behavior Analysis . Often, single-subject research takes the form of action research . No matter how unique or difficult the student's particular learning or behavioral problem, single-subject designs allow the researcher to study the problem in great detail. Furthermore, single-subject designs allow the teacher to function simultaneously as both teacher and researcher. Single-subject experiments should be designed to have high internal validity .
Internal validity is achieved in group designs primarily by random assignment.
This is not possible in single-subject designs, so other techniques are employed. Obtain Reliable Observations Single-subject designs typically require many observations of behavior. If the observations are unreliable, they will obscure any treatment effects. The simplest procedure is to target a single behavior for observation throughout the experiment. Single-subject designs require many more measurements because the behaviors of individuals varies even within short time intervals.