Research Article  |   December 2013
Using Statistical Process Control Charts to Study Stuttering Frequency Variability During a Single Day
 
Author Affiliations & Notes
  • Hamid Karimi
    Australian Stuttering Research Centre, The University of Sydney, New South Wales, Australia
  • Sue O’Brian
    Australian Stuttering Research Centre, The University of Sydney, New South Wales, Australia
  • Mark Onslow
    Australian Stuttering Research Centre, The University of Sydney, New South Wales, Australia
  • Mark Jones
    The University of Queensland, Brisbane, Australia
  • Ross Menzies
    Australian Stuttering Research Centre, The University of Sydney, New South Wales, Australia
  • Ann Packman
    Australian Stuttering Research Centre, The University of Sydney, New South Wales, Australia
  • 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 Mark Onslow: mark.onslow@sydney.edu.au
  • Editor: Jody Kreiman
    Editor: Jody Kreiman×
  • Associate Editor: Hans-Georg Bosshardt
    Associate Editor: Hans-Georg Bosshardt×
  • © American Speech-Language-Hearing Association
Article Information
Speech, Voice & Prosodic Disorders / Fluency Disorders / Research Article
Research Article   |   December 2013
Using Statistical Process Control Charts to Study Stuttering Frequency Variability During a Single Day
Journal of Speech, Language, and Hearing Research, December 2013, Vol. 56, 1789-1799. doi:10.1044/1092-4388(2013/12-0328)
History: Received October 19, 2012 , Revised February 5, 2013 , Accepted April 11, 2013
 
Journal of Speech, Language, and Hearing Research, December 2013, Vol. 56, 1789-1799. doi:10.1044/1092-4388(2013/12-0328)
History: Received October 19, 2012; Revised February 5, 2013; Accepted April 11, 2013

Purpose: Stuttering varies between and within speaking situations. In this study, the authors used statistical process control charts with 10 case studies to investigate variability of stuttering frequency.

Method: Participants were 10 adults who stutter. The authors counted the percentage of syllables stuttered (%SS) for segments of their speech during different speaking activities over a 12-hr day. Results for each participant were plotted on control charts.

Results: All participants showed marked variation around mean stuttering frequency. However, there was no pattern of that variation consistent across the 10 participants. According to control charts, the %SS scores of half the participants were indicative of unpredictable, out-of-control systems, and the %SS scores of the other half of the participants were not. Self-rated stuttering severity and communication satisfaction correlated significantly and intuitively with the number of times participants exceeded their upper control chart limits.

Conclusions: Control charts are a useful method to study how %SS scores might be applied to the study of stuttering variability during research and clinical practice. However, the method presents some practical problems, and the authors discuss how those problems can be solved. Solving those problems would enable researchers and clinicians to better plan, conduct, and evaluate stuttering treatments.

Acknowledgment
This research was supported by National Health and Medical Research Council of Australia Program Grant 633007.
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