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Table 2 Internal consistency and item scaling test including convergent and discriminant validity for the FACT-G and the EORTC QLQ-C30 subscales

From: Assessing whether EORTC QLQ-30 and FACT-G measure the same constructs of quality of life in patients with total laryngectomy

Scale

No.items

α

Mean ± SD

Convergent validity

discriminant validity

Range of correlation

Scaling success (percent)

Range of correlation

Scaling success (percent)

FACT-G

 Physical wellbeing

7

0.81

17.21 ± 5.42

0.51–0.84

7/7(100)

0.002–0.49

21/21(100)

 Social/family wellbeing

7

0.75

17.16 ± 5.15

0.41–0.79

7/7(100)

0.05–0.37

19/21(90)

 Emotional wellbeing

6

0.72

13.03 ± 4.79

0.19–0.81

5/6(83)

0.02–0.39

15/18(83)

 Functional wellbeing

7

0.61

14.73 ± 3.98

0.44–0.62

7/7(100)

0.01–0.27

21/21(100)

EORTC QLQ-C30

 Global health status/QOL

2

0.84

53.66 ± 22.35

0.92–0.94

2/2(100)

0.16–0.60

28/28(100)

Functional scales

 Physical functioning

5

0.69

75.25 ± 17.35

0.50–0.75

5/5(100)

0.03–0.62

62/70(88)

 Role functioning

2

0.83

76.26 ± 23.30

0.92–0.93

2/2(100)

0.01–0.68

28/28(100)

 Emotional functioning

4

0.87

62.69 ± 27.08

0.79–0.89

4/4(100)

0.03–0.71

56/56(100)

 Cognitive functioning

2

0.69

73.48 ± 25.88

0.86–0.87

2/2(100)

0.01–0.63

28/28(100)

 Social functioning

2

0.87

61.49 ± 28.62

0.93–0.94

2/2(100)

0.01–0.60

28/28(100)

Symptom scales/items

 Fatigue

3

0.67

32.32 ± 2.33

0.75–0.80

3/3(100)

0.05–0.65

42/42(100)

 Nausea and vomiting

2

0.58

12.37 ± 18.72

0.005–0.10

0/2(0)

0.03–0.57

28/28(100)

 Pain

2

0.57

27.15 ± 21.64

0.82–0.85

2/2(100)

0.22–0.63

28/28(100)

 Dyspnoea

1

29.79 ± 31.97

1

1/1(100)

0.13–0.62

14/14(100)

 Insomnia

1

26.26 ± 27.94

1

1/1(100)

0.06–0.61

14/14(100)

 Appetite

1

25.00 ± 26.17

1

1/1(100)

0.003–0.51

14/14(100)

 Constipation

1

27.27 ± 33.41

1

1/1(100)

0.03–0.32

14/14(100)

 Diarrhoea

1

13.13 ± 23.57

1

1/1(100)

0.03–0.51

14/14(100)

 Financial difficulties

1

57.83 ± 34.91

1

1/1(100)

0.19–0.62

14/14(100)