Accelerated Failure Time Model to Explore the Perception Response Times of Drivers in Simulated Car-Following Scenarios

Table 3

Parameter estimates of Weibull AFT models with heterogeneity.

Variable	Estimate	S.E.	Z-test	95% IC	Exp (β)	Percentage change (%)
Gender
Female versus male	−0.036	0.099	−0.36	(−0.230, 0.159)	0.965	−3.5
Age group
Middle-aged versus young	−0.155	0.086	−1.80	(−0.324, 0.013)	0.856	−14.4
Level of WMC
The top quartile versus the bottom quartile	−0.239	0.122	−1.96	(−0.478, 0.000)	0.787	−21.3
The second quartile versus the bottom quartile	−0.250	0.119	−2.10	(−0.484, −0.016)	0.779	−22.1
The third quartile versus the bottom quartile	−0.232	0.113	−2.06	(−0.453, −0.011)	0.793	−20.7
Level of cognitive load
Cognitive load versus baseline load	0.204	0.043	4.75	(0.120, 0.288)	1.226	22.6
Lead vehicle’s deceleration rate
0.6 g versus 0.3 g	−0.021	0.034	−0.60	(−0.089, 0.047)	0.979	−2.1
THW	0.072	0.034	2.10	(0.005, 0.139)	1.075	7.5
Constant	0.172	0.111	1.55	(−0.045, 0.390)
(scale parameter)	3.890	0.221	23.91	(3.480, 4.348)
Theta	1.562	0.287	2.42	(1.089, 2.240)

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