Efficiency measurement with nonstationary variables: an application of panel cointegration techniques

In this paper, we apply panel cointegration tests and estimation techniques to obtain efficiency measures when it is uncertain whether the underlying technological relationship is structural or spurious due to possible non-stationarity of the data. We illustrate the dangers of efficiency measurement with panel data when integration and cointegration are not taken into account. We apply these techniques to efficiency measurement in U.S. airlines and find striking differences compared to results obtained with the traditional approach.