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Table 1 Fit of "Body Functions" item bank to Rasch model (after rescoring) (n = 266)

From: An initial application of computerized adaptive testing (CAT) for measuring disability in patients with low back pain

Item Location SE Individual Item Fit Residual Chi-Square Test Statistics p
WHODAS II – 1.1. In the last 30 days, how much difficulty did you have in concentrating on doing something for ten minutes? 1.518 0.140 0.879 8.326 0.040
WHODAS II – 1.3. In the last 30 days, how much difficulty did you have in analyzing and finding solutions to problems in day to day life? 3.084 0.151 0.042 0.498 0.919
WHODAS II – 1.5. In the last 30 days, how much difficulty did you have in generally understanding what people say? 2.245 0.153 -0.067 1.549 0.671
WHODAS II – 1.6. In the last 30 days, how much difficulty did you have in starting and maintaining a conversation? 3.521 0.166 -0.147 0.985 0.805
WHODAS II – 4.1. In the last 30 days, how much difficulty did you have in dealing with people you do not know? 3.878 0.196 0.383 3.269 0.352
WHODAS II – 4.2. In the last 30 days, how much difficulty did you have in maintaining a friendship? 4.110 0.221 -0.495 7.708 0.052
WHODAS II – 4.3. In the last 30 days, how much difficulty did you have in getting along with people who are close to you? 3.084 0.185 -1.006 1.652 0.648
WHODAS II – 4.4. In the last 30 days, how much difficulty did you have in making new friends? 3.953 0.208 0.021 2.977 0.395
WHODAS II – 6.3. In the last 30 days, how much of a problem did you have living with dignity because of the attitudes and actions of others? 2.264 0.162 0.725 1.592 0.661
WHODAS II – 6.5. In the last 30 days, how much have you been emotionally affected by your health condition? 0.317 0.159 -0.237 2.529 0.470
RDQ 13. My back is painful almost all of the time -2.956 0.179 -0.266 3.331 0.343
RDQ 18. I sleep less well because of my back -1.661 0.152 0.655 1.915 0.590
RDQ 22. Because of back pain, I am more irritable and bad tempered with people than usual -2.762 0.173 -1.237 1.950 0.583
NHP 1. I'm tired all the time -3.530 0.203 -0.454 1.845 0.605
NHP 2. I have pain at night -2.146 0.159 0.671 3.030 0.387
NHP 4. I have unbearable pain 0.093 0.159 1.423 3.156 0.368
NHP 6. I've forgotten what it's like to enjoy myself -0.859 0.150 -0.427 3.987 0.263
NHP 7. I'm feeling on edge -1.948 0.156 -2.143 8.312 0.040
NHP 9. I feel lonely -0.680 0.151 -1.264 6.513 0.089
NHP 13. I'm waking up in the early hours of the morning -2.018 0.157 1.478 11.751 0.008
NHP 15. I'm finding it hard to make contact with people 1.062 0.180 -1.854 8.311 0.040
NHP 16. The days seem to drag -0.427 0.153 -2.530 9.019 0.029
NHP 20. I lose my temper easily these days -2.018 0.157 -0.733 0.632 0.889
NHP 21. I feel there is nobody that I am close to -0.512 0.152 -1.411 8.458 0.037
NHP 22. I lie awake for most of the night -1.129 0.150 -1.092 5.465 0.141
NHP 23. I feel as if I'm losing control -0.904 0.150 -1.229 0.889 0.828
NHP 28. I'm in constant pain -2.208 0.160 -0.693 3.152 0.369
NHP 29. It takes me a long time to get to sleep -1.590 0.152 -0.154 6.140 0.105
NHP 30. I feel I am a burden to people -0.420 0.153 -0.630 0.055 0.997
NHP 31. Worry is keeping me awake at night -1.200 0.150 -2.118 5.686 0.128
NHP 32. I feel that life is not worth living 0.189 0.160 -0.895 1.724 0.632
NHP 34. I'm finding it hard to get along with people 1.249 0.186 -0.187 3.736 0.291
NHP 37. I wake up feeling depressed -1.601 0.152 -1.579 2.496 0.476
  1. WHODAS II: World Health Organization Disability Assessment Schedule II, RDQ: Roland Morris Low Back Pain Disability Questionnaire, NHP: Nottingham Health Profile, SE: Standard Error