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Table 2 Descriptive information and Cronbach’s alpha of the PDI total scale and its subscales

From: Reliability and validity of the Chinese version of the Psoriasis Disability Index (PDI) in Chinese patients with psoriasis

 

No. of items (score range)

Mean

SD

Percentile

% floor

% ceiling

Corrected item-total correlation

Cronbach's α

    

25

50

75

    

Chinese version

Daily activities

5(0–15)

5.3

3.5

3

5

8

5.2

1.7

0.58-0.70

0.82

Work

3(0–9)

2.5

2.5

0

2

4

27.9

4.5

0.62-0.72

0.86

Personal

2(0–6)

1.3

1.6

0

1

2

30.4

4

0.64-0.65

0.79

Leisure

4(0–12)

2.9

2.6

1

2

4

17.9

0.8

0.32-0.65

0.74

Treatment

1(0–3)

0.7

0.9

0

1

1

34.7

5.7

-a

-a

Total

15(0–45)

12.8

9.4

6

11

18

3.1

0.5

0.37-0.74

0.91

English version b

Total score

15(0–45)

7.3

7.2

2

-

11

14.7

0

-

-

  1. a Scale consists of one item.
  2. b From a validation study done in the United States [32].