ارتباط میان توسعه اقتصادی و کشش درآمد تقاضای واردات

In both the international economics and economic development literatures, it has been noted that there is a tendency for the income elasticity of import demand to rise over time. In the first part of the paper, data from a large sample of countries is used to show that this tendency seems to be a general phenomenon. However, the previous studies on this issue have not offered a general explanation of this tendency. The second part of the paper develops a general explanation of why the income elasticity of import demand rises with the level of GDP per capita. The starting point of the analysis is that the process of economic development normally is associated with a rising share of manufacturing in GDP. In turn, this tends to increase the share of manufactured relative to nonmanufactured imports. Given that the income elasticity of import demand is higher for manufactured than nonmanufactured imports, the changing composition of imports increases the overall elasticity of import demand. The empirical results indicate that this is a plausible explanation for why the income elasticity of import demand rises with the level of GDP per capita.

Since the mid-1980s, the ratio of imports to GDP has been rising in virtually all countries. Because of this, imports are becoming an increasingly important factor in determining the rate of growth of real GDP. In attempting to manage this growth, policymakers rely on forecasts of changes in real GDP. In this environment, forecasts of imports are becoming an increasingly important component of the overall forecast. In turn, this means that the determinants of imports become more important over time. In general, these determinants are real GDP, import prices, domestic prices, and the exchange rate. While all of these factors are important, imports do not respond to these determinants over the same time frame. Imports respond rather slowly to changes in relative prices and the exchange rate. On the other hand, imports respond to changes in real GDP within one to two quarters. In determining the short-run evolution of imports, changes in real GDP have more of an impact than either relative prices or exchange rates. The income elasticity of demand for imports becomes a more important factor in determining imports in the short run and by extension changes in real GDP. As a result, the size of this elasticity becomes important for policymakers concerned with short-run changes in real GDP. Any significant changes in this elasticity have obvious implications for the accuracy of macroeconomic forecasts and the efficacy of macroeconomic policy. The same is true on the other side of the trade balance. An important determinant of exports is the level of foreign real GDP. Changes in real GDP in other countries can quickly affect the level of exports with noticeable impacts on the domestic economy.

One of the more important variables in international economics is the income elasticity of import demand. Its importance is derived from the large and rising percentage of GDP accounted for by imports. In attempting to account for either current or future changes in GDP, this elasticity becomes more important over time both for GDP accounting, macroeconomic policy, and exchange rate policy. If this elasticity is changing over time, then policy decisions are being made with faulty information. The summary of our results given below indicates that this may well be the case. The income elasticity of the demand for imports seems to be rising over time. The motivating purpose of this paper was to investigate the proposition that the income elasticity of import demand for imports seems to rise over time. The previous literature had posited that this was the case but was deficient in two respects. First, this increase had not been documented for many countries. Second, there was no general explanation of why this was true. In the second part of the paper, we have shown that the income elasticity of import demand does seem to rise with the level of real GDP per capita. This result holds even after adjusting for the level of industrialization, possible regional influences, and the presence of countries with very high income elasticities of demand for imports.