Table 4.
Diagnostic statistics for the smaller item set of DEMQOL (23 items)
| Item | Location | Fit Residual | ChiSq | p | DIF | Item residual correlations | |
|---|---|---|---|---|---|---|---|
| r | Correlation with item | ||||||
| 2. Worried or anxious | 0.349 | 0.886 | 3.54 | 0.94 | ns | 0.21, 0.15, 0.08, 0.02 | 9, 4, 7, 14 |
| 4. Frustrated | 0.546 | 0.257 | 2.66 | 0.98 | ns | 0.15, 0.15, 0.14, 0.12, 0.06, 0.06 | 2, 11, 12, 7, 13 |
| 7. Sad | 0.080 | −0.255 | 6.58 | 0.68 | ns | 0.18, 0.15, 0.14, 0.08, 0.06, 0.01 | 12, 8, 9, 2, 4, 11 |
| 8. Lonely | −0.206 | 2.222 | 5.59 | 0.78 | ns | 0.40, 0.15, 0.15, 0.04 | 20, 7, 12, 9 |
| 9. Distressed | −0.391 | −2.395 | 7.04 | 0.63 | ns | 0.21, 0.14, 0.12, 0.10, 0.05, 0.04 | 2, 7, 4, 12, 11, 8 |
| 11. Irritable | 0.007 | 0.361 | 1.66 | 1.00 | ns | 0.15, 0.14, 0.05, 0.02, 0.01 | 4, 12, 9, 11, 7 |
| 12. Fed-up | 0.425 | 0.361 | 2.20 | 0.99 | ns | 0.18, 0.15, 0.14, 0.14, 0.10, 0.04 | 7, 8, 4, 11, 9, 13 |
| 13. Things you wanted but couldn’t | 0.829 | 4.077 | 12.51 | 0.19 | ns | 0.06, 0.04, 0.02, 0.01 | 4, 12, 11, 26 |
| 14. Forgetting happened recently | 0.654 | −1.100 | 4.43 | 0.88 | ns | 0.15, 0.12, 0.08, 0.06, 0.06, 0.02 | 17, 19, 18, 15, 16, 2 |
| 15. Forgetting who people are | −0.043 | 2.511 | 6.68 | 0.67 | ns | 0.11, 0.10, 0.08, 0.07, 0.06, 0.02, 0.02 | 17, 16, 18, 19, 15, 24, 26 |
| 16. Forgetting what day it is | 0.135 | 4.339 | 11.45 | 0.25 | ns | 0.12, 0.10, 0.06, 0.03, 0.02, 0.02 | 17, 15, 14, 19, 18, 26 |
| 17. Thoughts being muddled | 0.126 | −2.376 | 8.27 | 0.51 | ns | 0.22, 0.15, 0.13, 0.12, 0.11, 0.06, 0.03 | 19, 14, 18, 16, 15, 24, 27 |
| 18. Difficulty making decisions | −0.103 | −2.777 | 8.08 | 0.53 | ns | 0.16, 0.13, 0.08, 0.08, 0.02, 0.02 | 19, 17, 14, 15, 16, 24 |
| 19. Poor concentration | 0.298 | −2.338 | 6.86 | 0.65 | ns | 0.22, 0.16, 0.12, 0.07, 0.03, 0.02 | 17, 18, 14, 15, 16, 24 |
| 20. Not having enough company | −0.415 | −0.981 | 5.01 | 0.83 | ns | 0.40, 0.07, 0.07, 0.02 | 8, 22, 25, 23 |
| 21. Get on with people close to you | −0.422 | −1.291 | 5.21 | 0.82 | ns | 0.41, 0.11, 0.06, 0.06 | 22, 24, 23, 25 |
| 22. Getting the affection you want | −0.525 | 0.328 | 6.63 | 0.68 | ns | 0.41, 0.07, 0.07, 0.07, 0.03 | 21, 20, 23, 25, 24 |
| 23. People not listening to you | −0.479 | −0.989 | 5.73 | 0.77 | ns | 0.17, 0.07, 0.06, 0.04, 0.02 | 24, 22, 21, 25, 20 |
| 24. Making yourself understood | −0.337 | −1.792 | 4.27 | 0.89 | ns | 0.17, 0.11, 0.06, 0.06, 0.03, 0.02, 0.02, 0.02 | 23, 21, 17, 25, 22, 15, 18, 19 |
| 25. Getting help when needed | −0.511 | −2.833 | 5.07 | 0.83 | ns | 0.07, 0.07, 0.06, 0.06, 0.04, 0.03, 0.02 | 20, 22, 21, 24, 23, 28, 26 |
| 26. Getting to the toilet in time | −0.267 | 3.543 | 17.96 | 0.04 | ns | 0.02, 0.02, 0.02, 0.01 | 15, 16, 25, 13 |
| 27. How you feel in yourself | 0.016 | −4.440 | 14.24 | 0.11 | ns | 0.21, 0.03 | 28, 17 |
| 28. Overall health | 0.232 | −1.848 | 6.27 | 0.71 | ns | 0.21, 0.03 | 27, 25 |
Fit residuals in bold are outside the acceptable range of +/− 2.5. Location = average item threshold location (logit). ChiSq = chi square value; p = chi square probability. DIF = differential item functioning; ns = non-significant. None of the chi square tests is statistically significant at p < 0.01 (Bonferroni corrected)