Table 5.
Reliability and validity outcomes of computer vision syndrome-F4 and -Smart questionnaires
| Variables | CVS-F4 | CVS-Smart |
|---|---|---|
| Number of questionnaire items | 30 | 5 |
| Responses | Binary response (Yes/No format) for each questionnaire item | 3 responses/answers/choices for each questionnaire item |
| Reliability indices | ||
| Kuder–Richardson 20 formula | 0.81 (high reliability) | - |
| Cronbach’s alpha coefficient | - | 0.860 (high reliability) |
| Guttman split-half coefficient | - | 0.805 (high reliability) |
| Interrater reliability*: | ||
| -Significance at 0.01 | - | Significant for all questionnaire items |
| -Correlation interpretation | - | Moderate-to-strong correlation for all questionnaire items (range: 0.51–0.69) |
| Validity indices | ||
| I. Content validity (by five experts) | ||
| -Content validity ratio | 1 for each of 24 items and | one per five questionnaire items |
| -Content validity index | 0.6 for each of remaining 6 items | 1 (perfect content validity) |
|
II. Face validity (by non-experts)
Face validity was evaluated by some medical student participants |
Good, clear, relevant, appropriate, and comprehensive, but lengthy with some items seeming less important | Strong, clear, relevant, appropriate, concise, simple, easy to understand, comprehensive, and all five items are of identical importance |
| III. Construct validity | ||
| A. Confirmatory factor analysis | ||
| -Comparative fit index | 0.896 (good fit) | 0.986 (good fit) |
| -Tucker–Lewis index | 0.860 (good fit) | 0.971 (good fit) |
| -Root mean square error of approximation | 0.084 (mediocre fit) | 0.078 (mediocre fit) |
| B. Spearman’s rho correlation coefficient | ||
| -Significance at 0.01 | - | Significant for all questionnaire items |
| -Correlation interpretation | - | Strong correlation for all questionnaire items (range: 0.77–0.83) |