up: [[Experimental Study Design]] Tags: # Small-N Designs Small-N designs (otherwise known as case studies) are experiments done with a small sample size where as [[Large-N designs]] are experiments done with a large sample size. Usually Small-N designs are [[Types of Experimental Design#Within Subject Design|within subject designs]] because of how small the sample size is. **Small-N designs treat participants as separate experiments in themselves.** This means a small sample size could still be a large-N design if participants were measured in groups. ## What are the three types of Small-N designs? #### Stable baseline design A participant is observed for a series of days or weeks without any treatment to establish a stable baseline before a treatment is given. #### Multi baseline design Participants are given the intervention at staggered times to rule out some time related confounds. Another version of multi baseline design is wait list design in which all participants will receive a treatment but one group gets it before others. #### Reversal design Participants are given a treatment and then the treatment is taken away for a period to see if the observed effect reverses. They are then given the treatment again. #### What are Single-N designs? Single-N designs are exactly like small-N designs but they only study one participant. ### Validities in Small-N designs Internal Validity #### External validity This is usually the hardest validity to find in small-n designs because it's hard to generalize the results to a population. However, sometimes external validity is not being sought by the researchers. See [[In Defense of External Invalidity]]. For example, therapists looking for something that helps an individual patient. However there are some methods to validate external validity nonetheless. For example, researchers can [[Triangulation|triangulate]] results from the small-N study by combining them with results of other small-N studies. Construct validity Statistical validity Reference: Related: [[Quasi Experimental Design]] Created: [[22-09-2022]]