From: A brief guide to the selection of quality of life instrument
Likely to be a good Longitudinal questionnaire | Likely to be a good Cross-sectional questionnaire |
---|---|
Short (typically 1 – 40 items) | Long (typically 20 – 100 items) |
Multi-response (e.g., 7-response) format item | Simple (e.g., binary or tertiary) response format |
Limited severity range: Items describe problems common to most patients, or only in the population to be studied | Items cover the whole severity range of QOL deficit |
No items showing floor or ceiling effects (i.e., items where >70% respond at either end of the scale) within target population | Items with floor and ceiling effects should be included |
Items must be relevant to most patients | Items need not be relevant to all patients |
Items irrelevant to the disease should not be included (unless the scale is used to test for iatrogenic change) | Items irrelevant to the disease should not be included (unless the scale is to be sensitive to co-morbidity) |