In 2007, Germany changed network access regulation in the natural gas sector and introduced a so-called entry-exit system. The re-regulation’s spot market effects remain to be examined. <p> We use cointegration analysis and a state space model with time-varying coefficients to study the...</p>

Supervised dimension reduction methods have been extensively applied in different scientific fields like biology and medicine in recent years. However, they have hardly ever been used in micro economics, and in particular cost function modeling. Nonetheless, these methods can also be useful in...

Since the 1990s, efficiency and benchmarking analysis has increasingly been used in network utilities research and regulation. A recurrent concern is the effect of environmental factors that are beyond the influence of firms (observable heterogeneity) and factors that are not identifiable...