Choosing Among Techniques for Quantifying Single-Case Intervention Effectiveness

Manolov, R., Solanas, A., Sierra, V. and Evans, J.J. (2011) Choosing Among Techniques for Quantifying Single-Case Intervention Effectiveness. Behavior Therapy, 42(3), pp. 533-545. (doi: 10.1016/j.beth.2010.12.003)

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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

Item Type:Articles
Glasgow Author(s) Enlighten ID:Evans, Professor Jonathan
Authors: Manolov, R., Solanas, A., Sierra, V., and Evans, J.J.
College/School:College of Medical Veterinary and Life Sciences > School of Health & Wellbeing > Mental Health and Wellbeing
Journal Name:Behavior Therapy
Published Online:30 March 2011

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