Table 3 Negative Binomial Regressions for Number of Person-Trips: All Purposes and Recreational Purposes
Table 3
Negative Binomial Regressions for Number of Person-Trips: All Purposes and Recreational Purposes
| Variable | Beta | SE | t-stat | P-value | Negative binomial regression | Poisson regression | |
|---|---|---|---|---|---|---|---|
| Dependent variable: number of person-trips for all purposes | Constant | 1.672 | 0.012 | 138.00 | 0.000 | ||
| HH members per vehicle owned | 0.255 | 0.004 | 59.20 | 0.000 | |||
| Income per household member | -3.16E-06 | 2.77E-07 | -11.40 | 0.000 | |||
| Population density | -4.42E-06 | 6.10E-07 | -7.25 | 0.000 | |||
| Vehicle age | -0.014 | 0.001 | -20.80 | 0.000 | |||
| Weekend day indicator | 0.100 | 0.007 | 13.50 | 0.000 | |||
| SUV indicator | 0.045 | 0.012 | 3.85 | 0.000 | |||
| Pickup indicator | -0.164 | 0.011 | -14.90 | 0.000 | |||
| Minivan indicator | 0.302 | 0.011 | 28.50 | 0.000 | |||
| Over-dispersion parameter | 0.351 | 0.004 | 97.10 | 0.000 | |||
| Log-likelihood Function for number of person-trips for all purposes | Constant only | -121,113.3 | -160,951.3 | ||||
| Convergence | -117,983.1 | -148,642.7 | |||||
| Pseudo-R2 | 0.026 | 0.076 | |||||
| Dependent variable: number of person-trips for recreational purposes | Constant | 0.485 | 0.021 | 22.80 | 0.000 | ||
| HH members per vehicle owned | 0.204 | 0.008 | 25.90 | 0.000 | |||
| Income per household member | -3.14E-06 | 4.73E-07 | -6.60 | 0.000 | |||
| Population density | -6.12E-06 | 1.09E-06 | -5.60 | 0.000 | |||
| Vehicle age | -0.018 | 0.001 | -15.60 | 0.000 | |||
| Weekend day indicator | 0.590 | 0.014 | 41.40 | 0.000 | |||
| SUV indicator | 0.005 | 0.021 | 0.20 | 0.814 | |||
| Pickup indicator | -0.292 | 0.019 | -15.20 | 0.000 | |||
| Minivan indicator | 0.308 | 0.020 | 15.70 | 0.000 | |||
| Over-dispersion parameter | 1.009 | 0.011 | 93.40 | 0.000 | |||
| Log-likelihood function for number of person-trips for recreational purposes | Constant only | -82,460.37 | -10,6536.4 | ||||
| Convergence | -80,612.10 | -99,753.51 | |||||
| Pseudo-R2 | 0.022 | 0.064 |
Number of observations: 41,538 vehicles
Model form: Number of person-trips ~ negative binomial with expected value
exp(β′X) and non-negative over-dispersion parameter