Effect Size for Single-Subject Design in Phonological Treatment Purpose The purpose of this study was to document, validate, and corroborate effect size (ES) for single-subject design in treatment of children with functional phonological disorders; to evaluate potential child-specific contributing variables relative to ES; and to establish benchmarks for interpretation of ES for the population. Method Data ... Research Article
Research Article  |   October 01, 2015
Effect Size for Single-Subject Design in Phonological Treatment
 
Author Affiliations & Notes
  • Judith A. Gierut
    Indiana University, Bloomington
  • Michele L. Morrisette
    Indiana University, Bloomington
  • Stephanie L. Dickinson
    Indiana University, Bloomington
  • Disclosure: The authors have declared that no competing interests existed at the time of publication.
    Disclosure: The authors have declared that no competing interests existed at the time of publication. ×
  • Correspondence to Judith A. Gierut: gierut@indiana.edu
  • Editor: Jody Kreiman
    Editor: Jody Kreiman×
  • Associate Editor: Ben A. M. Maassen
    Associate Editor: Ben A. M. Maassen×
Article Information
Development / Speech, Voice & Prosodic Disorders / Research Issues, Methods & Evidence-Based Practice / Attention, Memory & Executive Functions / Speech, Voice & Prosody / Speech / Research Articles
Research Article   |   October 01, 2015
Effect Size for Single-Subject Design in Phonological Treatment
Journal of Speech, Language, and Hearing Research, October 2015, Vol. 58, 1464-1481. doi:10.1044/2015_JSLHR-S-14-0299
History: Received October 22, 2014 , Revised April 14, 2015 , Accepted July 12, 2015
 
Journal of Speech, Language, and Hearing Research, October 2015, Vol. 58, 1464-1481. doi:10.1044/2015_JSLHR-S-14-0299
History: Received October 22, 2014; Revised April 14, 2015; Accepted July 12, 2015
Web of Science® Times Cited: 1

Purpose The purpose of this study was to document, validate, and corroborate effect size (ES) for single-subject design in treatment of children with functional phonological disorders; to evaluate potential child-specific contributing variables relative to ES; and to establish benchmarks for interpretation of ES for the population.

Method Data were extracted from the Developmental Phonologies Archive for 135 preschool children with phonological disorders who previously participated in single-subject experimental treatment studies. Standard mean differenceall with correction for continuity was computed to gauge the magnitude of generalization gain that accrued longitudinally from treatment for each child with the data aggregated for purposes of statistical analyses.

Results ES ranged from 0.09 to 27.83 for the study population. ES was positively correlated with conventional measures of phonological learning and visual inspection of learning data on the basis of procedures standard to single-subject design. ES was linked to children's performance on diagnostic assessments of phonology but not other demographic characteristics or related linguistic skills and nonlinguistic skills. Benchmarks for interpretation of ES were estimated as 1.4, 3.6, and 10.1 for small, medium, and large learning effects, respectively.

Conclusion Findings have utility for single-subject research and translation of research to evidence-based practice for children with phonological disorders.

Acknowledgments
This research was supported by the National Institute on Deafness and Other Communication Disorders of the National Institutes of Health under Grants DC001694, DC00433, and DC00076 (PI: Gierut) and DC00012 (PI: Pisoni). The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. The authors thank Dan Dinnsen for comments on the manuscript and Grace Reynolds and Maria Miller for assisting with data analyses.
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