Masked Visual Analysis: Minimizing Type I Error in Visually Guided Single-Case Design for Communication Disorders Purpose Single-case experimental designs are widely used to study interventions for communication disorders. Traditionally, single-case experiments follow a response-guided approach, where design decisions during the study are based on participants' observed patterns of behavior. However, this approach has been criticized for its high rate of Type I error. In masked ... Tutorial
Tutorial  |   June 10, 2017
Masked Visual Analysis: Minimizing Type I Error in Visually Guided Single-Case Design for Communication Disorders
 
Author Affiliations & Notes
  • Tara McAllister Byun
    NYU Steinhardt School of Culture, Education, & Human Development
  • Elaine R. Hitchcock
    Montclair State University, Bloomfield, New Jersey
  • John Ferron
    University of South Florida, Tampa
  • 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 Tara McAllister Byun: tara.byun@nyu.edu
  • Editor: Julie Liss
    Editor: Julie Liss×
  • Associate Editor: Tanya Eadie
    Associate Editor: Tanya Eadie×
Article Information
Research Issues, Methods & Evidence-Based Practice / Language Disorders / Speech / Tutorial
Tutorial   |   June 10, 2017
Masked Visual Analysis: Minimizing Type I Error in Visually Guided Single-Case Design for Communication Disorders
Journal of Speech, Language, and Hearing Research, June 2017, Vol. 60, 1455-1466. doi:10.1044/2017_JSLHR-S-16-0344
History: Received August 30, 2016 , Revised December 5, 2016 , Accepted January 20, 2017
 
Journal of Speech, Language, and Hearing Research, June 2017, Vol. 60, 1455-1466. doi:10.1044/2017_JSLHR-S-16-0344
History: Received August 30, 2016; Revised December 5, 2016; Accepted January 20, 2017

Purpose Single-case experimental designs are widely used to study interventions for communication disorders. Traditionally, single-case experiments follow a response-guided approach, where design decisions during the study are based on participants' observed patterns of behavior. However, this approach has been criticized for its high rate of Type I error. In masked visual analysis (MVA), response-guided decisions are made by a researcher who is blinded to participants' identities and treatment assignments. MVA also makes it possible to conduct a hypothesis test assessing the significance of treatment effects.

Method This tutorial describes the principles of MVA, including both how experiments can be set up and how results can be used for hypothesis testing. We then report a case study showing how MVA was deployed in a multiple-baseline across-subjects study investigating treatment for residual errors affecting rhotics. Strengths and weaknesses of MVA are discussed.

Conclusions Given their important role in the evidence base that informs clinical decision making, it is critical for single-case experimental studies to be conducted in a way that allows researchers to draw valid inferences. As a method that can increase the rigor of single-case studies while preserving the benefits of a response-guided approach, MVA warrants expanded attention from researchers in communication disorders.

Acknowledgments
This research was supported by NIH R03DC 012883 (McAllister Byun) and also benefited from a travel fellowship to attend the IES Single-Case Design and Analysis Institute 2014 (McAllister Byun). The authors also express their gratitude to the following individuals: for study implementation and data management, Roberta Lazarus, Lauren Dioguardi, and Melissa Lopez; for programming support, José Ortiz and Daniel Szeredi; and for comments on the article, graduate students in NYU's reading group on single-case design for communication disorders. Many thanks as well to all participants (including online participants) and their families for their cooperation throughout the study.
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