Table 3.
The parameter estimates, standard errors, t statistics and confidence level of different models of non-injury crashes, deaths and injuries on the Addis Ababa - Adama/Hawassa main road from 2002-2011
| Models and variables | Coefficient | Standard error | t statistics | Confidence interval |
|---|---|---|---|---|
| Non-injury crashes: Prais- |
|
|
|
|
| Winston regression (Model 1) |
|
|
|
|
| Intercept β0 |
295.1577 |
33.8195 |
8.73*** |
(228.17, 362.14) |
| Baseline trend β1 |
3.248131 |
.8461874 |
3.84*** |
(1.57, 4.92) |
| Level change β2 |
-40.19842 |
49.2873 |
-.82 |
(-137.81, 57.42) |
| Trend change β3 |
-5.096253 |
1.538459 |
-3.31** |
(-8.14, -2.05) |
| Death: Segmented regression (Model 2) |
|
|
|
|
| Intercept β0 |
150.1638 |
15.06675 |
9.97*** |
(120.32, 1.10) |
| Baseline trend β1 |
.3492265 |
.3795861 |
.92 |
(-.40, 1.10) |
| Level change β2 |
3.599756 |
22.71791 |
.16 |
(-41.39, 48.59) |
| Trend change β3 |
-1.961251 |
.6828936 |
-2.87** |
(-3.31, -.60) |
| Injuries: Segmented regression (Model 3) |
|
|
|
|
| Intercept β0 |
96.99802 |
22.13401 |
4.38*** |
(53.16, 140.83) |
| Baseline trend β1 |
1.862395 |
.557636 |
3.34** |
(.75, 2.96) |
| Level change β2 |
-43.5782 |
33.37405 |
-1.31 |
(-109.68, 22.52) |
| Trend change β3 | -1.489333 | 1.003214 | -1.48 | (-3.47, .49) |
***p < 0.0001, **p < 0.01, p < 0.05.