Table 2 Test-retest reliability, measurement errors, Cronbach’s alpha and item-total correlation values for NDI-U (n = 46)

2.09 ± 0.91

1.85 ± 0.87

0.86 (0.75–0.92)

0.32

0.89

0.69

0.91 ± 1.07

0.91 ± 1.05

0.98 (0.96–0.99)

0.15

0.42

0.67

2 ± 1.38

1.91 ± 1.31

0.96 (0.94–0.98)

0.27

0.75

0.34

1.78 ± 1.13

1.70 ± 1.13

0.97 (0.94–0.98)

0.19

0.53

0.73

1.50 ± 1.34

1.43 ± 1.31

0.98 (0.97–0.99)

0.19

0.53

0.49

1.39 ± 1.24

1.41 ± 1.20

0.98 (0.96–0.99)

0.17

0.47

0.84

1.30 ± 1.01

1.37 ± 1.06

0.95 (0.91–0.97)

0.23

0.64

0.67

1.45 ± 1.08

1.46 ± 1.07

0.93 (0.88–0.96)

0.28

0.78

0.81

1.26 ± 1.18

1.20 ± 1.09

0.96 (0.93–0.98)

0.22

0.61

0.61

1.50 ± 1.28

1.46 ± 1.33

0.97 (0.95–0.99)

0.22

0.61

0.89

15.18 ± 8.58

14.70 ± 8.37

0.99 (0.98–0.99)

0.84

2.33

NA