# 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
1. 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)