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Table 3 Diagnostic statistics for DEMQOL-Proxy (26 items)

From: DEMQOL and DEMQOL-Proxy: a Rasch analysis among those diagnosed with dementia

  Subsample dementia Full sample
Item Location Fit Residual ChiSq p DIF Location Fit Residual ChiSq p DIF
2. Worried or anxious 0.456 − 0.264 6.83 0.34 ns 0.637 0.278 3.76 0.93 ns
3. Frustrated 0.502 − 0.052 4.28 0.64 ns 0.574 −0.677 4.27 0.89 ns
5. Sad − 0.464 − 0.175 13.58 0.03 ns −0.330 −1.455 7.01 0.64 ns
7. Distressed −0.532 −1.198 6.24 0.40 ns −0.425 −2.095 6.48 0.69 ns
9. Irritable 0.000 0.985 14.32 0.03 PWD sex 0.052 0.919 3.07 0.96 PWD sex
PWD age
Relation
10. Fed-up 0.216 −0.266 13.69 0.03 ns 0.287 −1.249 3.05 0.96 ns
12. Memory in general 0.623 1.094 4.72 0.58 ns 0.664 1.529 6.49 0.69 ns
13. Forgetting that happened long ago −0.610 2.793 12.90 0.04 ns −0.467 4.704 19.16 0.02 ns
14. Forgetting that happened recently 1.507 −0.172 5.16 0.52 ns 1.462 0.373 4.66 0.86 ns
15. Forgetting people’s names 0.755 0.478 2.61 0.86 ns 0.684 2.627 8.42 0.49 ns
16. Forgetting where he/she is −0.754 0.399 9.51 0.15 ns −0.866 −0.539 5.87 0.75 ns
17. Forgetting what day it is 0.632 1.541 2.52 0.87 ns 0.451 2.045 4.86 0.85 Severity
18. Thoughts being muddled 0.732 −2.251 21.98 0.00 Carer age
Relation
0.604 −3.813 25.07 0.00 ns
19. Difficulty making decisions 0.535 −1.790 17.28 0.01 ns 0.458 −3.475 15.15 0.09 ns
20. Making him/herself understood −0.253 0.748 13.65 0.03 ns −0.201 2.456 3.60 0.94 ns
21. Keeping him/herself clean −0.685 2.373 17.93 0.01 ns −0.744 2.423 7.96 0.54 ns
22. Keeping him/herself looking nice −0.746 1.470 17.92 0.01 ns −0.702 2.008 9.74 0.37 ns
23. Getting from the shops −0.436 −0.795 3.45 0.75 ns −0.501 −0.922 3.61 0.94 ns
24. Using money to pay −0.411 −0.573 4.80 0.57 ns −0.578 −1.365 5.59 0.78 ns
25. Looking after finances −0.161 1.300 7.54 0.27 ns −0.304 0.915 9.25 0.41 ns
26. Things taking longer 0.378 −1.195 8.67 0.19 ns 0.402 −2.987 13.39 0.15 ns
27. Getting in touch with people −0.376 −0.843 7.23 0.30 ns −0.472 −1.684 6.39 0.70 ns
28. Not having enough company −0.446 1.012 6.61 0.36 PWD sex
PWD age
Carer age
Relation
−0.352 2.197 7.79 0.56 PWD sex
Carer age
Relation
29. Not being able to help other people −0.542 0.012 4.29 0.64 ns −0.472 1.136 5.80 0.76 ns
30. Not playing a useful part −0.281 −0.383 7.64 0.27 ns −0.231 −2.067 8.27 0.51 ns
31. His/her physical health 0.360 0.783 10.10 0.12 ns 0.369 2.762 9.22 0.42 ns
  1. Note. 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 α = 0.01 (Bonferroni-corrected: p < 0.000385)