Abbreviation	Definition
ANNs	Artificial Neural Networks
BCC	Banker, Charnes and Cooper
CCR	Charnes, Cooper and Rhodes
CO2	Carbon Dioxide
DEA	Data Envelopment Analysis
DMU	Decision-Making Unit
GARCH	Generalized AutoRegressive Conditional Heteroskedasticity
GDP	Gross Domestic Product
LR	Likelihood Ratio
LSTM	Long Short-Term Memory
MAE	Mean Absolute Error
MSE	Mean Square Error
R2	Coefficient of Determination
RNN	Recurrent Neural Network
SBM	Slack Based Measure
SFA	Stochastic Frontier Analysis
VAR	Vector Autoregression