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Research methods in clinical psychology: An introduction for students and practitioners Chris Barker, Nancy Pistrang, and Robert Elliott. CHAPTER 9 Small-N designs. Small-N Designs: Overview. Single case experiments Naturalistic case studies. Traditions of small-N research.
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Research methods in clinical psychology:An introduction for students and practitionersChris Barker, Nancy Pistrang, and Robert Elliott CHAPTER 9 Small-N designs
Small-N Designs:Overview • Single case experiments • Naturalistic case studies
Traditions of small-N research • Single case studies in medicine and neuropsychology • Operant behaviourism • Shapiro Personal Questionnaire • Idiographic personality research
Single case experiments(N=1 designs) • AB design • Reversal (ABAB) design • Multiple baseline design • Changing criterion design
AB design (Use OH with representation of design)
ABAB design (Use OH with representation of design)
Multiple baseline design (Use OH with representation of design)
Changing criterion design (Use OH with representation of design)
Single case experiments: data analysis and generalisation • Data displayed on graph • but can use statistical methods • Generalisation: • Multiple single case design • Clinical replication series
Naturalistic case studies • Narrative case studies • Systematic case studies • Time-series designs
Narrative case studies • Can be used for: • documenting the existence of a phenomenon • disproving a universal proposition • demonstrating a new intervention • generating causal hypotheses • Problems: • reliance on memory • “narrative smoothing” • anecdotal
Systematic case studies:increasing internal validity 1. systematic, quantitative (versus anecdotal) data 2. multiple assessments of change over time 3. multiple cases 4. change in previously chronic or stable problems 5. immediate or marked effects following the intervention (Kazdin, 1981; Hayes et al., 1999)
Time-series designs • aim: to evaluate causal processes • use correlational methods
Small-N designs: Conclusions • Good at: • looking at phenomena in depth • disconfirming theories by providing counter-examples • generating hypotheses/theory • Poor at: • establishing typicalities or general laws • but “clinical replication series” can test limits of external validity
Methodological pluralism • combine large-N and small-N approaches • Examples: • Rogers’ (1967) “silent young man” • Parry et al.’s (1986) “anxious executive”