Subal C. Kumbhakar and Efthymios G. Tsionas, "Stochastic Error Specification in Primal and Dual Production Systems", Journal of Applied Econometrics, Vol. 26, No. 2, 2011, pp. 270-297. The data used in this paper were obtained from Spiro Stefanou, whom we acknowledge in the paper. Since we are not authorized to make the data public, the data in the file (KT_data.txt) is a subset of the data used in our paper (data for the year 1999 were dropped). We also do not use the name of the utilities but provide an id for them. The data is in one ASCII file called kt-data.txt. It is an ASCII file in DOS format, and it is zipped in the file kt-data.zip. Unix/Linux users should use "unzip -a". Total number of obs=1065 Number of years=13 max Number of plants=82 max Panel is unbalanced The following variables are in the data file (in columns). w_l w_f w_k x_l x_f x_k y id year tc where w_l is price index of labor. w_f is the price index of fuel. w_k is the user price of capital. x_l, x_f, x_k are labor, fuel and capital, respectively. tc is total cost defined as the cost of labor, capital, and fuel. y is output. id is the id of the utility. All data sources and relevant references for construction of the variables are given in paper.