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Table 1 Possible values and characteristics of coal miners with and without CWP

From: Identification and classification of high risk groups for Coal Workers' Pneumoconiosis using an artificial neural network based on occupational histories: a retrospective cohort study

Variable Name Possible values and number of examples
  Category With CWP
(n = 236)
Without CWP
(n = 14419)
χ2(P)
Birth (year of birthday) (7)Before 1930 52 201 1821.977
(<0.0001)
  (6)1930- 129 696  
  (5)1940- 40 871  
  (4)1950- 14 3652  
  (3)1960- 1 6168  
  (2)1970- 0 2736  
  (1)After 1980 0 95  
Age (age in years of first exposure to dust) (7)< 20 60 6328 60.003
(<0.0001)
  (6)20- 100 5786  
  (5)25- 51 1614  
  (4)30- 16 454  
  (3)35- 8 167  
  (2)40- 1 61  
  (1)≥45 0 9  
Year (year of first exposure to dust) (7)Before 1950 14 33 1992.257
(<0.0001)
  (6)1950- 149 669  
  (5)1960- 57 759  
  (4)1970- 15 3026  
  (3)1980- 1 6164  
  (2)1990- 0 3764  
  (1)After 2000 0 4  
Job (occupational category) (4)Tunneling 201 4949 274.335
(<0.0001)
  (3)Combining 9 670  
  (2)Mining 23 2892  
  (1)Helping 3 5908  
Time 1(years) Duration of dust exposure 23.38 ± 7.07 18.31 ± 7.05 120.561
(<0.001)
Time 2(years) Duration of ex-dust exposure 6.09 ± 7.96 2.49 ± 5.72 47.613
(<0.001)
  1. The number of ( ) is possible value of different variables in neural network analysis