RT Journal Article T1 Five levels of performance and two subscales identified in the computer-vision symptom scale (CVSS17) by Rasch, factor, and discriminant analysis A1 González Pérez, Mariano A1 Susi García, María Del Rosario A1 Barrio De Santos, Ana Rosa A1 Antona Peñalba, Beatriz AB Purpose: To quantify the levels of performance (symptom severity) of the computer-vision symptom scale (CVSS17), confirm its bifactorial structure as detected in an exploratory factor analysis, and validate its factors as subscales.Methods: By partial credit model (PCM), we estimated CVSS17 measures and the standard error for every possible raw score, and used these data to determine the number of different performance levels in the CVSS17. In addition, through discriminant analysis, we checked that the scale's two main factors could classify subjects according to these determined levels of performance. Finally, a separate Rasch analysis was performed for each CVSS17 factor to assess their measurement properties when used as isolated scales.Results: We identified 5.8 different levels of performance. Discriminant functions obtained from sample data indicated that the scale's main factors correctly classified 98.4% of the cases. The main factors: Internal symptom factor (ISF) and external symptom factor (ESF) showed good measurement properties and can be considered as subscales.Conclusion: CVSS17 scores defined five different levels of performance. In addition, two main factors (ESF and ISF) were identified and these confirmed by discriminant analysis. These subscales served to assess either the visual or the ocular symptoms attributable to computer use. PB Public Library Science SN 1932-6203 YR 2018 FD 2018-08-28 LK https://hdl.handle.net/20.500.14352/13018 UL https://hdl.handle.net/20.500.14352/13018 LA eng NO Received: September 27, 2017; Accepted: July 30, 2018; Published: August 28, 2018Editor: José M. González-Méijome, Universidade do Minho, PORTUGAL DS Docta Complutense RD 23 ago 2024