# Table 5 Diagnostic statistics for the smaller item set of DEMQOL-Proxy (26 items)

Item Location Fit Residual ChiSq p DIF Item residual correlations
r Correlation with item
2. Worried or anxious 0.637 0.278 3.76 0.93 ns 0.33, 0.32, 0.29, 0.23, 0.16, 0.08 3, 7, 5, 10, 9, 12
3. Frustrated 0.574 −0.677 4.27 0.89 ns 0.34, 0.33, 0.33, 0.29, 0.26, 0.04 9, 2, 10, 7, 5, 12
5. Sad −0.330 −1.455 7.01 0.64 ns 0.42, 0.32, 0.29, 0.26, 0.20, 0.06, 0.01 10, 7, 2, 3, 9, 28, 31
7. Distressed −0.425 −2.095 6.48 0.69 ns 0.32, 0.32, 0.29, 0.27, 0.24 2, 5, 3, 10, 9
9. Irritable 0.052 0.919 3.07 0.96 PWD sex
PWD age
Relation
0.34, 0.32, 0.24, 0.20 3, 10, 7, 5
10. Fed-up 0.287 −1.249 3.05 0.96 ns 0.42, 0.33, 0.32, 0.27, 0.23, 0.08, 0.02 5, 3, 9, 7, 2, 28, 31
12. Memory in general 0.664 1.529 6.49 0.69 ns 0.13, 0.08, 0.04, 0.04, 0.03 14, 2, 3, 15, 31
13. Forgetting happened long ago −0.467 4.704 19.16 0.02 ns 0.13, 0.04, 0.01 15, 16, 27
14. Forgetting happened recently 1.462 0.373 4.66 0.86 ns 0.26, 0.22, 0.22, 0.14, 0.13, 0.05 15, 17, 18, 19, 12, 16
15. Forgetting people’s names 0.684 2.627 8.42 0.49 ns 0.26, 0.14, 0.13, 0.10, 0.04, 0.04, 0.03, 0.03 14, 17, 13, 16, 12, 18, 19, 20
16. Forgetting where he/she is −0.866 −0.539 5.87 0.75 ns 0.23, 0.16, 0.10, 0.07, 0.05, 0.04, 0.03 17, 18, 15, 19, 14, 13, 20
17. Forgetting what day it is 0.451 2.045 4.86 0.85 Severity 0.27, 0.23, 0.22, 0.14, 0.14 18, 16, 14, 15, 19
18. Thoughts being muddled 0.604 −3.813 25.07 0.00 Age 0.36, 0.27, 0.22, 0.16, 0.14, 0.04 19, 17, 14, 16, 20, 15
19. Difficulty making decisions 0.458 −3.475 15.15 0.09 ns 0.36, 0.16, 0.14, 0.14, 0.07, 0.05, 0.03 18, 20, 14, 17, 16, 26, 15
20. Making him/herself understood −0.201 2.456 3.60 0.94 ns 0.16, 0.14, 0.03, 0.03, 0.01 19, 18, 15, 16, 27
21. Keeping him/herself clean −0.744 2.423 7.96 0.54 ns 0.64, 0.10, 0.06, 0.04, 0.02, 0.02 22, 23, 24, 31, 26, 29
22. Keeping him/herself looking nice −0.702 2.008 9.74 0.37 ns 0.64, 0.11, 0.05, 0.05, 0.02 21, 23, 29, 31, 24
23. Getting from the shops −0.501 −0.922 3.61 0.94 ns 0.23, 0.11, 0.10, 0.07, 0.06, 0.03 24, 22, 21, 25, 27, 26
24. Using money to pay −0.578 −1.365 5.59 0.78 ns 0.47, 0.23, 0.08, 0.06, 0.04, 0.02 25, 23, 27, 21, 26, 22
25. Looking after finances −0.304 0.915 9.25 0.41 ns 0.47, 0.13, 0.07 24, 27, 23
26. Things taking longer 0.402 −2.987 13.39 0.15 ns 0.13, 0.11, 0.07, 0.07, 0.05, 0.04, 0.03, 0.02 30, 27, 29, 31, 19, 24, 23, 21
27. Getting in touch with people −0.472 −1.684 6.39 0.70 ns 0.13, 0.11, 0.11, 0.08, 0.08, 0.06, 0.03, 0.01, 0.01 25, 26, 29, 24, 27, 23, 30, 13, 20
28. Not having enough company −0.352 2.197 7.79 0.56 PWD sex
Carer age
Relation
0.10, 0.08, 0.08, 0.08, 0.06, 0.01 30, 10, 27, 29, 5, 31
29. Not able help other people −0.472 1.136 5.80 0.76 ns 0.39, 0.14, 0.11, 0.08, 0.07, 0.05, 0.02 30, 31, 27, 28, 26, 22, 21
30. Not playing useful part −0.231 −2.067 8.27 0.51 ns 0.39, 0.18, 0.13, 0.10, 0.03 29, 31, 26, 28, 27
31. His/her physical health 0.369 2.762 9.22 0.42 ns 0.18, 0.14, 0.07, 0.05, 0.04, 0.03, 0.02, 0.01 30, 29, 26, 22, 21, 12, 10, 5
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)