Qualitative research is a method that has been developed to bring details of individual responses into a format that gives some measure of the richness of detailed case study while still guarding against Type I errors (accepting as true something that is actually false) due to individual variability.

Small numbers of people with a common problem are given a particular therapy and their reports are analyzed in great individual detail. Analyses of these details also provide a basis for building theories as to how a therapy may work to make a person better.