Abstract
Abstract In this paper, (2SLS) & (3SLS) is used to estimate the simultaneous equation of grains (wheat, maize, rice, barley) for the period (1961-2002). The variables have been considered as direct effects on the world prices of the grains (production, export, import, exchange in the stock, foreigners reserves, the number of the world population, advancement technological). The simultaneous equations have been estimated by the same methods after adding the economic crises to the system (wars, drought, financial and monetary crises and oil shocks) to view the effects also on the world prices of the grains. The (SAS. 9) package is used to obtain the results. .
