There are questions about the external validity of the results because single-subject experiments frequently only involve a small number of subjects.
A type of quantitative research known as single-subject studies includes closely examining each participant's behavior in a small sample size. It should be noted that the phrase "single-subject" does not necessarily suggest that only one participant is being examined; rather, it usually refers to a group of two to ten.
Single subject research design is a sort of research methodology that involves monitoring a single phenomena repeatedly over time (often a behavior), and it is typically used to test interventions.
Changes on the DV can be measured using data gathered before, during, and after the intervention.
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