Analysis and Prediction on Vehicle Ownership Based on an Improved Stochastic Gompertz Diffusion Process

Table 2

Predict values by improved SGDP and general Gompertz of vehicle ownership per 1000 people in the United States.

	Real data	Gompertz	Improved; SGDP	95% confidence interval
2001	784.933	774.311	789.520	747.682	831.358
2002	808.761	774.517	794.774	749.836	839.712
2003	798.673	774.637	798.819	752.811	844.827
2004	797.935	774.760	804.472	757.099	851.845
2005	810.240	774.846	810.261	761.024	859.498
2006	815.994	774.899	815.489	765.278	865.700
2007	818.134	774.928	819.591	767.680	871.502
2008	820.714	774.934	820.557	766.282	874.832
Standard error		34.103	5.721	—	—