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Measurement properties of fine motor scale of Peabody developmental motor scales-second edition: a Rasch analysis
1School of Education, James Cook University, Townsville, Australia.
Insights
Rasch analysis of the Peabody Developmental Motor Scales-Second Edition fine motor scale suggests revisions are needed. Simplifying scales and removing misfitting items can improve assessment of children's fine motor abilities.
Area of Science:
- Developmental psychology
- Pediatric occupational therapy
- Psychometrics
Background:
- The Peabody Developmental Motor Scales-Second Edition (PDMS-2) is widely used to assess fine motor skills in children.
- Evaluating the psychometric properties of assessment tools is crucial for accurate diagnosis and intervention planning.
- Rasch analysis provides a robust method for examining item and scale performance.
Purpose of the Study:
- To investigate the measurement properties of the PDMS-2 fine motor scale using Rasch analysis.
- To assess rating scale performance, unidimensionality, and differential item functioning (DIF) of the PDMS-2 fine motor subtests.
- To identify potential areas for revision in the PDMS-2 for improved clinical utility.
Main Methods:
- A prospective study involving 419 children in Taiwan, including typically developing children and those with fine motor delays.
- Administration of the PDMS-2, specifically the 26-item grasping and 72-item visual-motor integration subtests.
- Application of partial credit Rasch analysis to evaluate item and scale characteristics.
Main Results:
- Rasch analysis supported collapsing rating scale categories for many items into dichotomous responses.
- Unidimensionality was achieved for grasping and visual-motor integration subtests after removing misfitting items.
- The composite fine motor scale demonstrated unidimensionality, though some items showed DIF across sex and fine motor status. Significant ceiling effects were noted.
Conclusions:
- The findings provide a basis for revising the PDMS-2 fine motor scale in future editions.
- Simplifying rating scales and reducing misfitting items could enhance the unidimensionality and accuracy of fine motor assessments.
- Further research is needed to address ceiling effects and validate the revised scale for criterion-referenced measurement.
Objective:
To investigate the measurement properties (including rating scale performance, unidimensionality, and differential item functioning) of the fine motor scale of the Peabody Developmental Motor Scales-Second Edition in children, by using the Rasch analysis.
Design:
A total of 419 children (including 342 typically developing children and 77 children with fine motor delays or difficulties) were recruited in Taiwan for this prospective study. Each child was evaluated with the Peabody Developmental Motor Scales-Second Edition that consists of 26-item grasping and 72-item visual-motor integration subtests. Partial credit Rasch analysis was used for all analyses.
Results:
The Rasch analysis indicated that middle rating category for 19 grasping and 52 visual-motor integration items could be collapsed to allow only dichotomous response categories. Item fit analysis and principal component analysis suggested that the unidimensionality of the grasping and visual-motor integration subtests could be achieved after removal of two grasping and eight visual-motor integration misfitting items. All but 13 items in the composite scale could form a unidimensional construct of overall fine motor ability. Furthermore, only a few items were found to show differential item functioning across sex (ten items) or fine motor status (seven items). However, significant ceiling effects were found in the Peabody Developmental Motor Scales-Second Edition subtests and composite scale when applied to these typically developing children.
Conclusions:
Our results suggest grounds for the revision of the Peabody Developmental Motor Scales-Second Edition in a subsequent edition. Simplifying the rating scales and reducing the misfitting items in the subtests and composite scales might result in a unidimensional assessment of children's fine motor ability. Clinicians and researchers could use the reduced Peabody Developmental Motor Scales-Second Edition as a criterion-referenced outcome measure to document changes; however, further work is needed to reduce the ceiling effects.
