From observing the price in the past by studying the relation of time Engle-Granger Cointegration and by (1987), which is not limited to the same industry.
From the observation of prices in the past. The study of the time. Cointegration by Engle and Granger (1987), which is not only limited to the same industry.
From the observation of the price in the past. By studying the relationship of the model Cointegration according to Engle and Granger (1987) which are in the same industry.