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

Table 1

Summary statistics of the EUA prices’ and returns’ time series.

	EUA spot		EUA futures—DEC18		EUA futures—DEC19
	Prices	Returns	Prices	Returns	Prices	Returns
Mean	9.5310	0.0002	8.1587	0.0005	8.9314	0.0003
Median	7.5950	0.0000	7.1150	0.0011	7.4400	0.0011
Maximum	25.1900	0.2106	25.2400	0.2334	25.5600	0.2292
Minimum	2.6800	−0.4466	3.4800	−0.3638	3.7100	−0.3412
Std. dev.	4.8402	0.0329	3.8572	0.0319	4.7028	0.0311
Skewness	0.9405	−0.9881	1.9159	−0.9703	1.7496	−0.8960
Kurtosis	3.0575	20.4610	6.4729	17.4954	5.3223	15.7228
Jarque–Bera	360.3567	31419.3800	1898.8660	15185.5700	1300.7370	12174.6200