Elitist-opposition-based artificial electric field algorithm for higher-order neural network optimization and financial time series forecasting

Financial Innovation

Table 5 Statistical properties of energy price series

Statistic	Crude oil	Natural gas	Coal price
Minimum	10.0100	1.4820	9710
Mean	64.9122	3.7350	1.1244
Median	63.8600	2.9665	11,330
Variance	646.0576	3.7836	3.7159
Maximum	123.7000	9.3290	12,606
Standard deviation	25.4177	1.9452	609.5834
Skewness	0.28360	1.0896	− 0.6352
Kurtosis	2.3024	3.3357	3.3386
Correlation coefficient	− 0.3950	− 0.1196	− 0.4043
Lijung-box test	h = 1, p = 0.0000	h = 1, p = 0.0000	h = 0, p = 0.1199
KPSS test	h = 1, p = 0.0100	h = 1, p = 0.0100	h = 1, p = 0.0293
ADF test	h = 0, p = 0.6359	h = 0, p = 0.0564	h = 0, p = 0.5043
PP test	h = 0, p = 0.6359	h = 0, p = 0.9151	h = 0, p = 0.5043