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Table 2 Descriptive statistics calculated for seven expert operators by MRI subject group across 33 CM-I patients

From: Cerebellar tonsil ectopia measurement in type I Chiari malformation patients show poor inter-operator reliability

Measure

Subject group

Operator 1

Operator 2

Operator 3

Operator 4

Operator 5

Operator 6

Operator 7

Range (mm)

All

13.00

28.00

28.00

22.30

23.00

17.00

30.10

CM-Ia

8.50

10.00

16.20

13.40

10.00

12.00

15.30

CM-Is

11.80

16.00

14.90

16.70

15.00

13.00

19.90

Control

2.50

9.00

10.20

6.70

7.00

7.00

13.40

Mean (mm)

All

3.43

4.91

5.87

6.18

8.73

6.55

3.90

CM-Ia

3.49

6.00

7.55

6.73

8.50

7.67

4.85

CM-Is

6.10

9.09

10.65

10.37

12.73

8.73

9.34

Control

0.42

− 0.90

− 1.23

0.93

4.60

2.80

− 3.23

SD (mm)

All

3.65

5.33

6.23

5.48

4.99

4.27

6.90

CM-Ia

2.96

2.95

4.23

4.15

3.28

3.82

4.43

CM-Is

3.78

4.40

4.08

4.99

5.28

4.09

5.74

Control

0.86

2.43

2.78

2.00

2.01

1.89

3.63

Median (mm)

All

2.50

5.50

6.70

6.10

8.00

6.00

3.20

CM-Ia

3.50

6.00

7.70

6.65

10.00

7.50

4.20

CM-Is

5.00

8.00

10.50

8.30

10.00

7.00

7.90

Control

0.00

0.00

− 0.70

0.00

5.50

3.00

− 2.70

IQR (mm)

All

5.30

8.00

10.50

9.15

5.50

7.50

10.55

CM-Ia

5.83

5.00

6.40

6.95

5.75

6.75

6.90

CM-Is

5.80

4.00

6.70

7.50

9.00

7.00

8.80

Control

0.43

2.50

3.18

1.15

3.00

3.00

5.20

  1. CM-Ia type I Chiari malformation asymptomatic, CM-Is type 1 Chiari malformation symptomatic, IQR interquartile range, SD standard deviation