Refractive Status and Vision Profile: evaluation of psychometric properties and comparison of Rasch and summated Likert-scaling. [Post-print]
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Date
2006-04
Authors
Garamendi, Estibaliz
Pesudovs, Konrad
Stevens, Michael J
Elliott, David B
Journal Title
Journal ISSN
Volume Title
Publisher
Elsevier
Rights
Rights Holder
Abstract
The psychometric properties of the Refractive Status and Vision Profile (RSVP) questionnaire were evaluated using Rasch analysis. Ninety-one myopic patients from a refractive surgery clinic and general optometric practice completed the RSVP. Rasch analysis of the RSVP ordinal data was performed to examine for unidimensionality and item reduction. The traditional Likert-scoring system was compared with a Rasch-scored RSVP and a reduced item Rasch-scored RSVP. Rasch analysis of the original RSVP showed poor targeting of item difficulty to patient quality of life, items with a ceiling effect and underutilized response categories. Combining the underutilized response scales and removal of redundant and misfitting items improved the internal consistency and targeting of the RSVP, and the reduced 20-item Rasch scored RSVP showed greater relative precision over standard Likert scoring in discriminating between the two subject groups. A Rasch scaled quality of life questionnaire is recommended for use in refractive outcomes research.
Description
Keywords
Myopia, Refractive Errors, Sickness Impact Profile
Citation
Garamendi E., Pesudovs K., Stevens M J, Elliott DB. 2006. The Refractive Status and Vision Profile: evaluation of psychometric properties and comparison of Rasch and summated Likert-scaling. 'Vision Research'. Vol 46, Nos. 8-9, 1375-83.