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Table 2 Parameter estimates for heuristic ad hoc and near-optimal methods
From: Sensitivity of a real-time freeway crash prediction model to calibration optimality
Parameter | Category Level | Ad hoc | Near-optimal | ||
|---|---|---|---|---|---|
Estimate | Z-Value | Estimate | Z-Value | ||
θ | N/A | 1.518 | 9.78 | 1.929 | 4.81 |
λCOVV | [1] Low | −1.300 | −5.32 | −2.132 | −3.13 |
[2] Intermediate | −0.884 | −3.70 | −2.107 | −5.20 | |
[3] High | 0 | – | 0 | – | |
λCVS | [1] Low | −0.914 | −5.17 | −1.577 | −6.88 |
[2] Intermediate A | −1.735 | −8.11 | −1.203 | −7.40 | |
[3] Intermediate B | −1.496 | −7.32 | NA | NA | |
[4] High | 0 | – | 0 | – | |
λQ | [1] High Acceleration | −0.875 | −4.89 | −2.452 | −4.14 |
[2] Moderate Acceleration | −1.738 | −8.12 | −2.107 | −4.74 | |
[3] Moderate Deceleration | −1.508 | −7.44 | NA | NA | |
[4] High Deceleration | 0 | – | 0 | – | |
λR | Straight | −0.530 | −4.40 | −0.618 | −5.03 |
Merge Diverge | 0 | – | 0 | – | |
λP | Off-Peak | −1.254 | −8.16 | −1.544 | −6.41 |
Peak | 0 | – | 0 | – | |
β | N/A | 0.084 | 7.22 | 0.049 | 3.78 |