# Table 6 Differences in knowledge scores by regression models

Simple linear regression model Multiple linear regression model Linear regression model with backward elimination Multiple ordinal logistic regression model
Coefficient 95% CI Coefficient 95% CI Coefficient 95% CI Odds ratio 95% CI
Intervention group 7.881*** 3.160–12.602 7.646*** 3.381–11.911 7.602*** 3.428–11.776 4.724*** 2.140–10.428
Age −0.099 −0.264-0.065 − 0.161* −0.318--0.004 − 0.189** − 0.333--0.046 0.978 0.950–1.007
Sex (reference group = female) 4.201 −0.681-9.083 1.420 −2.943-5.784    1.543 0.719–3.310
Education (reference group = <high school) 1.625 −5.272-8.523 4.021 −2.577-10.619    1.428 0.443–4.600
Injury severity score −1.181*** −1.889--0.472 −0.842* −1.513--0.171 −0.923** − 1.54--0.300 0.771** 0.645–0.921
Transferred (reference group = non-transferred) −3.607 −9.261-2.046 −1.772 −6.724-3.181    0.633 0.258–1.549
Arrival time (reference group = other) 3.640 −1.235-8.516 0.775 −3.730-5.280    1.355 0.633–2.903
Physician 1.357 −5.072-7.787 −1.307 −7.200-4.587    1.107 0.405–3.030
Baseline knowledge score −0.319*** −0.44--0.190** −0.379*** − 0.508--0.249 −0.373*** − 0.494--0.252 0.946*** 0.922–0.971
Constant    36.410*** 22.119–50.701 40.522*** 30.693–50.351
R squared = 0.329 R squared = 0.316 Likelihood ratio test for model: χ2 = 54.18; p < 0.0001
1. *p < 0.05; **p < 0.01; ***p < 0.001. Sample size of regression model = 142