Assessment of reliable change using 95% credible intervals for the differences in proportions: a statistical analysis for case-study methodology

Rachael Unicomb, Kim Colyvas, Elisabeth Harrison, Sally Hewat

Research output: Contribution to journalArticleResearchpeer-review

Abstract

Purpose: Case-study methodology studying change is often used in the field of speech-language pathology, but it can be criticized for not being statistically robust. Yet with the heterogeneous nature of many communication disorders, case studies allow clinicians and researchers to closely observe and report on change. Such information is valuable and can further inform large-scale experimental designs. In this research note, a statistical analysis for case-study data is outlined that employs a modification to the Reliable Change Index (Jacobson & Truax, 1991). The relationship between reliable change and clinical significance is discussed. Example data are used to guide the reader through the use and application of this analysis. Method: A method of analysis is detailed that is suitable for assessing change in measures with binary categorical outcomes. The analysis is illustrated using data from one individual, measured before and after treatment for stuttering. Conclusions: The application of this approach to assess change in categorical, binary data has potential application in speech-language pathology. It enables clinicians and researchers to analyze results from case studies for their statistical and clinical significance. This new method addresses a gap in the research design literature, that is, the lack of analysis methods for noncontinuous data (such as counts, rates, proportions of events) that may be used in case-study designs.

LanguageEnglish
Pages728-739
Number of pages12
JournalJournal of Speech, Language, and Hearing Research
Volume58
Issue number3
DOIs
Publication statusPublished - 1 Jun 2015

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statistical analysis
Speech-Language Pathology
methodology
Research Design
pathology
Research Personnel
Communication Disorders
Stuttering
communication disorder
language
research planning
Methodology
Proportion
Statistical Analysis
Research
event
lack
Clinicians
Categorical
Speech-language Pathology

Cite this

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title = "Assessment of reliable change using 95{\%} credible intervals for the differences in proportions: a statistical analysis for case-study methodology",
abstract = "Purpose: Case-study methodology studying change is often used in the field of speech-language pathology, but it can be criticized for not being statistically robust. Yet with the heterogeneous nature of many communication disorders, case studies allow clinicians and researchers to closely observe and report on change. Such information is valuable and can further inform large-scale experimental designs. In this research note, a statistical analysis for case-study data is outlined that employs a modification to the Reliable Change Index (Jacobson & Truax, 1991). The relationship between reliable change and clinical significance is discussed. Example data are used to guide the reader through the use and application of this analysis. Method: A method of analysis is detailed that is suitable for assessing change in measures with binary categorical outcomes. The analysis is illustrated using data from one individual, measured before and after treatment for stuttering. Conclusions: The application of this approach to assess change in categorical, binary data has potential application in speech-language pathology. It enables clinicians and researchers to analyze results from case studies for their statistical and clinical significance. This new method addresses a gap in the research design literature, that is, the lack of analysis methods for noncontinuous data (such as counts, rates, proportions of events) that may be used in case-study designs.",
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Assessment of reliable change using 95% credible intervals for the differences in proportions : a statistical analysis for case-study methodology. / Unicomb, Rachael; Colyvas, Kim; Harrison, Elisabeth; Hewat, Sally.

In: Journal of Speech, Language, and Hearing Research, Vol. 58, No. 3, 01.06.2015, p. 728-739.

Research output: Contribution to journalArticleResearchpeer-review

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