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Table 3 Rasch-based fit statistics, ordering of the response scale thresholds, and reliability (n = 243)

From: Cross-cultural validity of four quality of life scales in persons with spinal cord injury

Items

δ

SE

z

Chi2

df

p

PCA eigen-value

t-test

%

Ï„

r

SWLS

          

Overall

   

78.54

10

0.000 b

1.97 c

3.3

7-steps

scale

0.88

Ideal life

0.35

0.05

-2.22

13.22

2

0.001b

  

disord

 

Life conditions

0.15

0.05

-1.70

15.10

2

0.001b

  

ord

 

Life satisfaction

-0.15

0.05

-1.13

7.21

2

0.027

  

ord

 

Got things I want

-0.25

0.06

0.37

3.10

2

0.212

  

disord

 

Change nothing in life

-0.11

0.05

6.41a

39.90

2

0.000b

  

disord

 

LISAT-9

          

Overall

   

50.60

18

0.000 b

2.06 c

7.4 b

6-step

scale

0.86

Life as a whole

-0.13

0.07

-2.04

19.15

2

0.000b

  

ord

 

Self care

0.08

0.05

0.60

1.16

2

0.561

  

ord

 

Vocational situation

0.26

0.06

-0.63

2.65

2

0.266

  

disord

 

Financial situation

0.19

0.06

1.43

0.22

2

0.897

  

ord

 

Leisure situation

0.34

0.06

-0.78

5.45

2

0.066

  

ord

 

Sexual life

0.97

0.06

-0.18

1.42

2

0.491

  

disord

 

Partner relations

-0.30

0.07

2.70a

11.20

2

0.004b

  

disord

 

Family life

-0.58

0.06

2.59a

8.23

2

0.016

  

disord

 

Contact with friends

-0.82

0.07

0.11

1.13

2

0.569

  

disord

 

PWI

          

Overall

   

15.62

16

0.480

1.96 c

8.7 b

11-steps

scale

0.92

Whole life

0.13

0.04

-1.25

5.12

2

0.077

  

ord

 

Living standard

0.02

0.04

1.07

1.56

2

0.457

  

ord

 

Health

0.20

0.04

3.14a

2.35

2

0.309

  

ord

 

Life achievement

0.05

0.04

1.04

0.62

2

0.735

  

ord

 

Relationships

-0.35

0.04

1.63

1.39

2

0.499

  

ord

 

Feeling safe

-0.11

0.04

-1.44

1.84

2

0.399

  

ord

 

Feel part of community

-0.09

0.04

-0.04

0.39

2

0.824

  

disord

 

Future security

0.14

0.04

-1.11

2.35

2

0.309

  

ord

 

WHOQoL-5

          

Overall

   

16.43

10

0.088

1.81

3.3

5-steps

scale

0.78

Health

0.30

0.09

0.32

1.49

2

0.475

  

ord

 

Activities of daily living

0.68

0.08

-0.29

0.94

2

0.627

  

ord

 

Relationships

-0.37

0.09

1.67

2.04

2

0.361

  

ord

 

Living place

-0.26

0.08

2.05

1.57

2

0.456

  

ord

 

Quality of life

-0.36

0.09

-1.83

10.40

2

0.005b

  

ord

 
  1. Index:
  2. a: Exceeds the critical value of z > +/-2.5
  3. b: Below the Bonferroni corrected probability level of p < 0.05/number of items (SWLS and PWI: p < 0.01; LISAT and PWI: p < 0.006)
  4. c: Exceeds the decision level for chance distribution of residuals with eigenvalue > 1.9
  5. d: Exceeds the 5% boundary for the number of significant independent t-tests based on the PCA results
  6. Abbreviations:
  7. SWLS: Satisfaction with life scale; LISAT: Life satisfaction questionnaire; PWI: Personal well-being index; WHOQoL: World Health Organization quality of life assessment; δ: Item location in logits (delta); SE: Standard error of item location; z: Standard normal distributed test value z; df: Degrees of freedom; p: Probability; PCA: Principal components analysis; t-test %: Percentage of significant independent t-tests; τ: Ordering of the response scale thresholds (tau); r: Person reliability index.