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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