An Optimized Grey GM(2,1) Model and Forecasting of Highway Subgrade Settlement

Table 3

Calculations and comparison of SOGM(2,1) and GM(2,1).

Time	Original data	SOGM(2,1)		GM(2,1)		GM(1,1)
		Fitting value	RPE	Fitting value	RPE	Fitting value	RPE
1	1.9892	2.0460	2.85%	1.9892	0.00%	1.9892	0
2	2.1702	2.2071	1.70%	2.2504	1.93%	2.2060	1.65%
3	2.3266	2.3426	0.69%	3.1339	13.68%	2.2964	1.30%
4	2.4332	2.4332	0.00%	4.3049	30.94%	2.3905	1.75%
5	2.4525	2.4525	0.00%	5.8496	54.14%	2.4885	1.47%
ARPE			1.05%		20.14%		1.23%