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Table 2 Chi-square test of variable independence

From: Exploring background risk factors for fatigue crashes involving truck drivers on regional roadway networks: a case control study in Jiangxi and Shaanxi, China

Risk contributes Jiangxi Shaanxi
χ2 p value Degree of freedom χ2 p value Degree of freedom
Driver factors
Gender 21.335** <0.001 1 17.463** <0.001 1
Marital status 46.412 0.062 3 31.231 0.157 3
Age 13.167** <0.001 2 21.117** <0.001 2
Driving experience 6.493** 0.003 3 7.062** <0.001 3
Occupation 5.615 0.186 6 8.133 0.105 6
Vehicle factors
Vehicle type 96.434** <0.001 1 104.212** <0.001 1
Commercial transport 51.601* 0.035 1 77.465* 0.008 1
Vehicle insurance 67.293* 0.044 1 44.047 0.092 1
Vehicle safety status 37.307 0.061 1 19.691 0.106 1
Vehicle brake performance 46.269** <0.001 1 8.673** <0.001 1
Roadway factors
Road type 117.355* 0.027 6 129.330* 0.016 6
Highway specific locations 56.493** <0.001 7 42.092** <0.001 7
Urban road specific locations 9.038 0.103 4 11.767 0.088 4
Pavement condition 11.764** <0.001 1 2.439** <0.001 1
Environment factors
Time of crash 23.697** <0.001 2 84.465* 0.031 2
Day of the week 4.611 0.084 1 6.731 0.089 1
Seasons 7.498* 0.037 3 14.222* 0.011 3
Public holiday 2.176 0.549 1 7.769 0.115 1
Weathercondition 8.335** <0.001 1 1.005** <0.001 1
Visibility condition 41.987** <0.001 1 17.343** <0.001 1
Traffic violations
Alcohol-impaired driving 33.764 0.298 1 23.646 0.089 1
Disregarding speed limits 11.028** <0.001 1 17.988** 0.003 1
Overloading 5.169** <0.001 1 3.497** <0.001 1
Risky following 22.633* 0.027 1 15.238 0.061 1
Failure to use seat belt 6.961 0.055 1 8.441 0.107 1
Cell phone use 46.376 0.086 1 98.493 0.064 1
Illegal meeting 5.108 0.161 1 4.767 0.055 1
Crash characteristics
Injury outcome 35.469** <0.001 3 26.894** <0.001 3
Type of collision 71.336* 0.033 5 89.471* 0.022 5
Collision partner 23.089** <0.001 4 16.746** 0.004 4
  1. * Significant at 5 % level; ** Significant at 0.5 % level