Effect Size for Single-Subject Design in Phonological Treatment

Area of Science:

• Speech-Language Pathology
• Developmental Psychology
• Applied Behavior Analysis

Background:

• Functional phonological disorders affect preschool children's speech sound development.
• Single-subject designs are crucial for evaluating interventions in this population.
• Standardized interpretation of effect size (ES) is needed for clinical decision-making.

Purpose of the Study:

• To document, validate, and corroborate effect size (ES) for single-subject designs in treating children with functional phonological disorders.
• To evaluate child-specific variables influencing ES.
• To establish benchmarks for interpreting ES in this population.

Main Methods:

• Data from 135 preschool children with phonological disorders were extracted from the Developmental Phonologies Archive.
• Standard mean difference (with continuity correction) was computed to quantify longitudinal generalization gain from treatment.
• Data were aggregated for statistical analyses.

Main Results:

• Effect size (ES) ranged from 0.09 to 27.83.
• ES positively correlated with phonological learning measures and diagnostic assessment performance.
• Benchmarks for small, medium, and large learning effects were estimated at 1.4, 3.6, and 10.1, respectively.

Conclusions:

• The findings support the utility of ES in single-subject research for phonological disorders.
• Validated ES benchmarks aid the translation of research into evidence-based practice.
• ES is a valuable metric for assessing treatment outcomes in children with phonological disorders.