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Table 1 Sociodemographic characteristics of injury cases and controls, 2012

From: Type A personality, hostility, time urgency and unintentional injuries among Chinese undergraduates: a matched case–control study

Characteristic Cases (n = 253) Controls (n = 253) Test statistic ( P-value)*
Quantitative or ordinal variables
Age (year, mean ± SD) 19.6 ± 1.17 19.6 ± 1.15 0.53 (0.594)
BMI (kg/m2, mean ± SD) 20.3 ± 2.56 20.2 ± 2.41 0.33 (0.744)
Annual per-capita income, Yuan    0.77 (0.442)
<2000 30 (11.9%) 30 (11.9%)  
2000 ~ 10000 59 (23.3%) 73 (28.9%)  
10000 ~ 30000 83 (32.8%) 71 (28.1%)  
30000 ~ 50000 36 (14.2%) 41 (16.2%)  
> 50000 45 (17.8%) 38 (15.0%)  
Dichotomous variables
  Exposure in pair  
  Both positive Only in case Only in control Both negative  
No. of siblings 44 62 59 88 0.514
Smoke 0 4 12 237 0.057
Drink 0 4 14 235 0.027
Sports 125 61 35 32 0.009
Club activity 96 69 48 40 0.054
  1. *: P value from paired samples t test (age, BMI), signed rank sum test (income), McNemar test (dichotomous variables).
  2. : Number of matched pairs in analysis is 253.