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Table 3 Rasch item and fit statistics for the NHPDa

From: Cross-diagnostic validity of the Nottingham health profile index of distress (NHPD)

   Item statistics c Fit statistics
Item b   Location SE Residual d Chi square e P-value
1 (1) Tired all the time -1.154 0.116 1.383 9.057 0.10681
2 (2) Pain at night -0.97 0.113 1.914 8.695 0.121867
3 (3) Things get me down -0.732 0.116 -1.841 5.612 0.345829
4 (4) Unbearable pain 0.425 0.14 -1.025 2.982 0.702838
5 (6) Joy forgotten 0.231 0.134 -2.03 9.32 0.09695
6 (7) Feeling on edge -1.127 0.112 0.257 4.383 0.495644
7 (8) Painful to change position -1.874 0.113 1.964 2.8 0.73085
8 (9) Feel lonely 0.297 0.136 0.521 2.791 0.732098
9 (12) Everything is an effort -0.95 0.113 -3.107 13.87 0.016456
10 (16) Days seem to drag 0.617 0.146 -1.448 3.529 0.619006
11 (20) Losing temper easily -0.409 0.12 1.321 7.45 0.189241
12 (21) Feel close to nobody 1.302 0.177 -0.336 6.317 0.276545
13 (22) Lie awake most of night 1.269 0.174 -1.313 1.735 0.884403
14 (23) Feel as if losing control 1.05 0.164 -1.557 9.758 0.082392
15 (26) Soon run out of energy -1.724 0.111 -1.318 5.277 0.383036
16 (28) In constant pain -0.356 0.12 -1.228 5.276 0.38318
17 (29) Takes long to get to sleep -0.485 0.118 0.928 4.264 0.512122
18 (30) Feel like a burden 0.075 0.13 -1.224 3.12 0.681545
19 (31) Kept awake by worries 0.904 0.157 -1.776 5.506 0.357274
20 (32) Life not worth living 0.815 0.153 -1.759 5.433 0.365301
21 (33) Sleep badly at night -0.966 0.113 0.799 1.207 0.944184
22 (34) Hard to get on with people 3.458 0.401 -0.896 1.985 0.85118
23 (37) Depressed when waking up 0.263 0.134 -2.121 6.171 0.28995
24 (38) In pain when sitting 0.042 0.129 0.193 7.798 0.167709
  1. a Performed with the sample divided into six class intervals according to person locations on the measured variables.
  2. b Original NHP item numbers in parenthesis.
  3. c Expressed in linear log-odds units (logits), with mean item location set at 0.
  4. d Residuals summarize the deviation of observed from expected responses. Deviation from the recommended [35] range of -2.5 to +2.5, indicating item misfit, are bold.
  5. e Higher values represent larger deviations from model expectations.
  6. NHPD, Nottingham Health Profile index of Distress; SE, standard error.