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

*p < 0.05; **p < 0.01; ***p < 0.001. Sample size of regression model = 142