BTS | Table 3 - Negative Binomial Regressions for Number of Person-Trips: All Purposes and Recreational Purposes

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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

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