نشریه اقتصاد مالی
پیاپی 11 (تابستان 1389)

Tourism is an activity where capital, infrastructure, knowledge and access to global marketing and distribution chains are critical. Foreign direct investment (FDI) is often considered one of the most effective engines for harnessing these elements. This study applies panel causality methods to investigate the relationship between FDI and tourism in Developing Countries during 1882-2002. For this purpose, the Hsiao's-Granger and Toda & Yamamoto (TY) causality tests used for investigating causality relationship between two variables.The model estimation reveal finds that there is unilateral causality from tourismto FDI. With respect to results of this study, the main implication policy is that the policy makers and economic planners should be adopting the suitable policies to improve tourism industry.

Nowadays air pollution as an important issue affects human health and economics phenomenon. In this study the relationship between economic growth and air pollution in selected provinces, has studied by use of Pollutant Standard Index. Results indicated that there is positive and significant relation between air pollution and economic growth in selected provinces. But Tehran and Khozestan and Khorasan Razavi provinces negatively affected. Results show that during the considered period, PSI as an indicator of environmental problem keeps on growing in time as long as the products in selected provinces keeps on growing. In other words, economic growth can't solve environmental problem during a time.

Nowadays there is a need for natural gas in almost every country. Considering the fact thatIslamic Republic of Iran is the second owner of natural gas reserves in the world,export of thisimportant factor would be one of the most inevitable subjects in our economy. Furthermore,thebenefits of oil export can be replaced by the benefits of gas export. But the high level ofdomestic consumption is of the most restrictive factors in promoting gas export.The main purpose of this paper is to determine an optimum price for Iran's natural gas exporttaking into account the domestic versus international demand for the fuel. In this way we practicea mathematical approach with a linear planning model,considering the concept ofopportunity cost in our analysis.In this way the optimum price would be reviled by adding theshadow price to the marginal cost. If we allocate our natural reserves to export,we should addthe minimum benefits of domestic consumption to marginal cost of production of gas. Obviouslyit will result in minimum price of gas export which is estimated to be 48.8 cent per cubic meter.