Table 5. Multiple comparisons of traffic accident occurrence between different road surface types.

Road types	Mean difference	Standard error	P value	95% Confidence Interval
				Lower Bound	Lower Bound
1 vs. 2	−49526.67	5118.08	0.000	−68788.28	−30265.05
1 vs. 3	7925.67	1806.88	0.033	728.47	15122.86
1 vs. 4	−35707.83	2660.88	0.000	−44425.80	−26989.87
2 vs. 3	57452.33	4823.82	0.000	37362.52	77542.14
2 vs. 4	13818.83	5204.30	0.188	−5349.97	32987.64
3 vs. 4	−43633.50	2038.32	0.000	−51839.23	−35427.77

Notes.

^aRoad types: (1= asphalt concrete pavement, 2= cement concrete pavement, 3= simple pavement, 4= unpaved roads).