Panel Data for DEA and Econometric Analyses

This study used two inputs variables; total hydropower installed capacity (megawatts per hour) and long-term average annual precipitation (in volume), and inputs costs; mean renewable energy feed-in tariffs (USD), and dam capacity per capita. One output variable which is hydroelectricity generation (terawatts per hour), was used to measure the cost-efficiency and its decompositions.

Static panel regression analysis in the second stage with a partial log form of the variables in each of the three model estimated.
where
Cost Efficiency (CE) of country (i) in period (t) obtained from the DEA in the first stage, inflation rate based on consumer price index (INF), log of gross domestic product (GDP), log of labour input (numbers of labours), investment proxy for research & development (INV).