Choosing Among Techniques for Quantifying Single-Case Intervention Effectiveness

• Published in: Behavior therapy Vol. 42; no. 3; pp. 533 - 545
• Main Authors: Manolov, Rumen, Solanas, Antonio, Sierra, Vicenta, Evans, Jonathan J.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Ltd 01.09.2011; Elsevier; Academic Press; Elsevier B.V
• Subjects: Behavior modification; Biological and medical sciences; Cognitive Development; Comparative Analysis; Comparative Effectiveness Research - methods; Comparative Effectiveness Research - statistics & numerical data; Computer Simulation; Confounding Variables; Data collection; Effect Size; Effectiveness studies; Evidence; Experimental psychology; Inspection; Inspections; Intervention; Investigació de cas únic; Magnitude; Medical sciences; Methodology. Experimentation; Models, Statistical; Monte Carlo method; Monte Carlo Methods; Monte Carlo simulation; Mètode de Montecarlo; Outcomes of Treatment; Psicologia experimental; Psychiatry; Psychology. Psychoanalysis. Psychiatry; Psychopathology. Psychiatry; Repeated; Research Design; Research Design - statistics & numerical data; Single subject research; Statistical Analysis; Techniques and methods; Variability; Case study; Human; Statistical method; Data analysis; Treatment; Methodology; Effect size; Treatment efficiency; Application method; Comparative study; Quantitative analysis
• ISSN: 0005-7894; 1878-1888; 1878-1888
• DOI: 10.1016/j.beth.2010.12.003

If single-case experimental designs are to be used to establish guidelines for evidence-based interventions in clinical and educational settings, numerical values that reflect treatment effect sizes are required. The present study compares four recently developed procedures for quantifying the magnitude of intervention effect using data with known characteristics. Monte Carlo methods were used to generate AB designs data with potential confounding variables (serial dependence, linear and curvilinear trend, and heteroscedasticity between phases) and two types of treatment effect (level and slope change). The results suggest that data features are important for choosing the appropriate procedure and, thus, inspecting the graphed data visually is a necessary initial stage. In the presence of serial dependence or a change in data variability, the nonoverlap of all pairs (NAP) and the slope and level change (SLC) were the only techniques of the four examined that performed adequately. Introducing a data correction step in NAP renders it unaffected by linear trend, as is also the case for the percentage of nonoverlapping corrected data and SLC. The performance of these techniques indicates that professionals' judgments concerning treatment effectiveness can be readily complemented by both visual and statistical analyses. A flowchart to guide selection of techniques according to the data characteristics identified by visual inspection is provided.