Table 1.
Quality criteria and thresholds of acceptability for measurement properties (adapted from Wilberforce et al., 2016)
| Measurement property | Rating | Threshold for acceptability |
|---|---|---|
| Internal consistency: overall scale | + | Cronbach alpha >.70 and < .95 |
| – | Cronbach alpha <.70 and > .95 | |
| Internal consistency: sub-scales | + | Cronbach alpha >.70 and < .95 |
| – | Cronbach alpha <.70 and > .95 | |
| Reliability | + | Intraclass Correlation Coefficient (ICC) > .70 OR Pearson’s Correlation Coefficient (r) > .80 |
| – | ICC < .70 OR r < .80 | |
| Content validity | + | Assessed in target population that items are a complete representation of concept under measurement and that all items are relevant |
| – | Questionnaire is incomplete OR contains irrelevant items | |
| Structural validity | + | Factors explain 50% of variance |
| – | Factors explain less than 50% of variance | |
| Cross-cultural validity | + | Original factor structure confirmed OR no differential item functioning |
| – | Original factor structure not confirmed OR important differential item functioning observed |