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Table 4 Rasch analysis results by individual items

From: Developing a dementia-specific health state classification system for a new preference-based instrument AD-5D

  Response category ordering Item range Fit residuals χ2 p-value DIF
Interpersonal environment
Item 4 Living situation Ordered −1.636 1.879 1.633 0.169 No DIF
Item 6 Family Ordered −1.428 2.012 −0.311 0.597 Age
Item 7 Staff Ordered −1.373 1.667 −1.481 0.247 No DIF
Item 8 Friends Ordered −1.634 1.932 0.207 0.977 No DIF
Item 12 Live with others Ordered −1.827 2.318 0.223 0.738 Age
Item 13 Make choices Ordered −1.978 2.467 0.113 0.951 ESL
Physical health
Item 1 Physical health Ordered −1.183 1.691 0.758 0.441 No DIF
Item 2 Energy Ordered −1.282 1.801 0.574 0.288 Gender
Self-functioning       
Item 9 Keep busy Ordered −2.291 2.588 0.000 0.934 Age
Item 10 Do fun things Ordered −1.958 2.563 0.029 0.725 No DIF
Item 11 Self-care Disordered (poor/fair) - - - - -
  1. Abbreviations: DIF differential item functioning