Single Case Research

1. Single Case Research “Sometimes the magic works, sometimes it doesn’t” – Thomas Berger, Little Big Man. Instructor information

2. Single Case Research • Two major types • Single Subject Research • Quantitative study of change in behavior over time • Quasi-experimental methods • Did the system (person, family, community, etc.) change? • Case Study • In-depth analysis of a single system unit • Qualitative methods • How and why does the system function as it does?

3. Single Subject Research (SSR) • Limitations of using previous research • There may not be conclusive (or any) research evidence on the issue to be addressed. • The research evidence may show mixed or even contradictory results in several studies. • The research may not be generalizable to your specific client population. For example, studies with urban foster children may not generalize to rural youth. • Even when studies find consistently effective outcomes, not all people in the studies show positive outcomes. Usually, at least some people show no change or may even get worse.

4. Why use SSR • Need to know changes in an individual, not effectiveness for groups. • E.g. 70% are helped by parent training. • Provide information into the process of change, not just “yes / no.” • No complicated statistical analysis. • No need for control group. • Use with your own caseload. • Professional

5. Assumptions • Service is a problem solving experiment • Test hypotheses between client’s problems and given interventions. • Provides empirically validated knowledge. • Requirements • Objectives stated clearly. • Outcomes can be quantifiable. • Data is displayed appropriately.

6. Process • Establish target problems and goals • Operationalize goals as objectives • Identify short term objectives on the way to long term goals • Specify measures • Select a single subject design • Collect data (who collects the data?) • Implement the intervention • Continue to collect data • Evaluate the data

7. Define Goals • Dependent variable: goals of intervention • Define specifically and operationally • What will be measured? E.g. Tantrum • Frequency (how often) • Magnitude (how much: how loud or destructive) • Duration (how long) • Use valid and reliable scales when available • E.g. Depression or self-esteem scale • Use existing records when available • E.g. Attendance records, domestic violence reports • Use triangulation (multiple measures) when possible.

8. Baseline Phase • Time series design • Measurement before the intervention. • Three measurements are a minimum. • The more baseline measurements, the greater the certainty of a pattern. • Retrospective baseline uses client recall or previously collected data. • A = Baseline Phase; B = Intervention Phase A B

9. Intervention Phase • Continued measurement following introduction of the independent variable • Independent variable (Intervention) must be clearly described. • Measurement continues until goals are reached or a new strategy is needed. • Follow-up measurements may be included as Phase C. • Quasi-experimental designs can never “prove” the intervention caused the change, but can strongly “suggest.”

10. AB Design • Specify baseline and intervention periods • Label title, X axis, and Y axis • A = Baseline Phase; B = Intervention Phase

11. Multiple Baseline Design • Uses two or more indicators of change or two or more settings for measurement.

12. Multiple Component Design • Measures sequential interventions or level of a single intervention. (ABC Design) A = Baseline B = Play therapy C = Behavior therapy

13. Reversal Design • Remove the independent variable after the first B phase, then reintroduce it. • Provides better evidence that the intervention was responsible for the change. • Some changes can’t (or shouldn’t) be reversed A B A B

14. Changing Criterion Design • Monitor gradual changing of behavior • Change level of the objective as the goal is approached. E.g. cigarette reduction A B1 B2 B3 B4 B5 A B1 B2 B3 B4 B5

15. Success in SSR • Therapeutic Success • Reaching agreed upon goals • Use of cigarettes is ended • Experimental Success • Clear improvement but not all goals reached • Reduction from 35 to 5 cigarettes per day • Statistical Success • Reduction is greater than expected by chance • Reduction from 35 to 28 cigarettes per day • Change is statistical but not related to improved health

16. Methods to determine success • “Eyeballing” the data • Success is seen by looking at the graph • Clearly, no improvement has been made by the end of 10 weeks

17. Determining success (con). • Split middle method • Plot the mean of each half of the baseline scores. Draw a line and extent to Intervention (B) Phase. • If most point in the B Phase are above or below the line, the intervention is a success.

18. Determining Success (con.) • Standard Deviation Method • Use one or two standard deviations from the mean of the baseline in the intervention phase as a measure of success. A = Baseline B = Intervention 1 C = Intervention 2 D = Follow-up

19. Using SSR to inform practice • Advantages • Promotes effective services • Documents practice • Promotes research • Combine studies for generalization • Simple, no computers needed • Disadvantages • Impractical • No proven effectiveness • Baseline may be unstable or unavailable • Limited generalizability of results • Doesn’t explain, just describes • Lack of adequate time series measures

20. Case Study • Detailed, in-depth analysis of one or a few units. High external validity. • E.g. In-depth case studies • E.g. Organizational analysis • E.g. Subculture studies • Use of narrative, qualitative methods. • May include quantitative data as well. • Use in exploratory research. • Use in theory development related to cause and effect.