A Hybrid Forecasting Model for Nonstationary and Nonlinear Time Series in the Stochastic Process of CO₂ Emission Trading Price Fluctuation

Table 3

The Brock–Decher–Scheikman (BDS) test results for nonlinear time series.

Dimension	EUA spot		EUA futures—DEC18		EUA futures—DEC19
	BDS statistic	Prob.	BDS statistic	Prob.	BDS statistic	Prob.
2	0.1974	0.0000	0.1994	0.0000	0.2006	0.0000
3	0.3357	0.0000	0.3391	0.0000	0.3416	0.0000
4	0.4320	0.0000	0.4366	0.0000	0.4403	0.0000
5	0.4987	0.0000	0.5046	0.0000	0.5095	0.0000
6	0.5445	0.0000	0.5519	0.0000	0.5579	0.0000