We discuss econometric modeling with Prof. Aleksander Welfe from the University of Łódź and Warsaw School of Economics (SGH), Vice-President of the Polish Academy of Sciences.

Omodelowaniu ekonometrycznym opowiada prof. dr hab. Aleksander Welfe z Uniwersytetu Łódzkiego i Szkoły Głównej Handlowej w Warszawie, wiceprezes Polskiej Akademii Nauk.

The presence of a binary variable in the cointegrated VAR (CVAR) model is most often interpreted as the structural break affecting the data generating process. It is proved in the paper that to enjoy this interpretation the binary variable must appear simultaneously inside and outside the cointegration space. In order to test for the break we advocate to employ the Wald statistic, however, its critical values and the power had to be simulated separately for the possible change of the constant, the trend, and both. The experiments were designed for different sizes of the cointegrating space, number of variables, the span of the break, normally and t-distributed errors. It is shown that the power of the test depends mostly on the magnitude of the break and the sample size while other factors are of secondary importance. In order to test for the break at unknown period the supWald statistic was proposed.

The purpose of the article is to verify a hypothesis about the asymmetric pass-through of crude oil prices to the selling prices of refinery products (unleaded 95 petrol and diesel oil). The distribution chain is considered at three levels: the European wholesale market, the domestic wholesale market and the domestic retail market. The error correction model with threshold cointegration proved to be an appropriate tool for making an empirical analysis based on the Polish data. As found, price transmission asymmetry in the fuel market is significant and its scale varies depending on the level of distribution. The only exception is the wholesale price transmission to the domestic refinery price. All conclusions are supported by the cumulative response functions. The analysis sheds new light on the price-setting processes in an imperfectly competitive fuel market of a medium-sized, non-oil producing European country in transition.