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Table 2 Diagnostic statistics for DEMQOL (23 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 0.331 1.081 5.84 0.44 ns 0.349 0.886 3.54 0.94 ns
4. Frustrated 0.483 0.338 4.58 0.60 ns 0.546 0.257 2.66 0.98 ns
7. Sad 0.036 − 0.416 4.23 0.65 ns 0.080 −0.255 6.58 0.68 ns
8. Lonely − 0.238 1.948 19.47 0.00 ns −0.206 2.222 5.59 0.78 ns
9. Distressed −0.531 − 0.252 2.31 0.89 ns −0.391 −2.395 7.04 0.63 ns
11. Irritable 0.050 0.497 3.16 0.79 ns 0.007 0.361 1.66 1.00 ns
12. Fed-up 0.489 0.192 3.69 0.72 ns 0.425 0.361 2.20 0.99 ns
13. Things you wanted but couldn’t 0.735 2.408 21.20 0.00 ns 0.829 4.077 12.51 0.19 ns
14. Forgetting happened recently 0.673 −0.974 11.45 0.08 ns 0.654 −1.100 4.43 0.88 ns
15. Forgetting who people are 0.018 −0.207 6.34 0.39 ns −0.043 2.511 6.68 0.67 ns
16. Forgetting what day it is 0.375 1.342 5.28 0.51 ns 0.135 4.339 11.45 0.25 ns
17. Thoughts being muddled 0.280 −1.107 11.45 0.08 ns 0.126 −2.376 8.27 0.51 ns
18. Difficulty making decisions −0.123 −1.527 8.23 0.22 ns −0.103 − 2.777 8.08 0.53 ns
19. Poor concentration 0.305 −2.557 16.96 0.01 ns 0.298 −2.338 6.86 0.65 ns
20. Not having enough company −0.468 1.750 16.53 0.01 ns −0.415 −0.981 5.01 0.83 ns
21. Get on with people close to you −0.366 −2.134 10.65 0.10 ns −0.422 −1.291 5.21 0.82 ns
22. Getting the affection you want −0.564 −1.112 6.15 0.41 ns −0.525 0.328 6.63 0.68 ns
23. People not listening to you −0.635 0.290 5.56 0.47 ns −0.479 −0.989 5.73 0.77 ns
24. Making yourself understood −0.319 −1.278 6.88 0.33 PWD sex −0.337 −1.792 4.27 0.89 ns
25. Getting help when needed −0.466 −1.278 11.54 0.07 ns −0.511 −2.833 5.07 0.83 ns
26. Getting to the toilet in time −0.202 1.596 16.87 0.01 ns −0.267 3.543 17.96 0.04 ns
27. How you feel in yourself 0.011 −2.538 16.88 0.01 ns 0.016 −4.440 14.24 0.11 ns
28. Overall health 0.125 −0.816 5.74 0.45 ns 0.232 −1.848 6.27 0.71 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 familywise α = 0.01 (Bonferroni-corrected: p < 0.000435)