TABLE 3.

Data quality and Internal Consistency of the NDI, n = 150.

NDI ∗	Missing, n (%)	Mean (SD)	Lowestn (%)	Highestn (%)	Cronbach Alpha/Item-Total Correlation
NDI total score (0–100)	0	41.09 (20.72)	0	0	0.70
1. Pain intensity	0	2.60 (0.84)	1 (0.7)	1 (0.7)	0.68
2. Personal care	0	1.36 (0.97)	28 (18.7)	0	0.67
3. Lifting	0	1.56 (1.18)	28 (18.7)	1 (0.7)	0.66
4. Reading	55 (36.7)†	4.03 (3.86)	19 (20.0)	1 (0.7)	0.67
5. Headache	1 (0.7)	1.96 (1.35)	14 (9.3)	4 (2.7)	0.70
6. Concentration	61 (40.7)	4.33 (3.94)	20 (22.5)	0	0.67
7. Work	0	1.45 (1.14)	27 (18.0)	3 (2.0)	0.67
8. Driving	0	1.27 (1.13)	40 (26.7)	0	0.67
9. Sleeping	0	1.07 (1.11)	57 (38.0)	0	0.67
10. recreation	0	0.91 (0.93)	52 (34.7)	1 (0.7)	0.69

NDI indicates Neck Disability Index.

^∗Items are scored on a 0–5point scale (5 represents more disability).

^†Non respondents were illiterate.