Estimating Time Variation of Market Power: Case of U.S. Soybean Exports
Estimating Time Variation of Market Power: Case of U.S. Soybean Exports
复制标题
估计市场力量的时间变化：以美国大豆出口为例
DOI：
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发表时间：
2012
期刊：
影响因子：
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通讯作者：
T. Nakajima
中科院分区：
文献类型：
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作者：
T. Nakajima
随着新实证产业组织理论方法的发展，越来越多的研究对各种农产品供应链中卖方和/或买方的市场势力进行了评估。然而，他们中的许多人并没有捕捉到样本期间市场势力的时间变化，即使他们使用长时间序列数据。如果市场势力的程度实际上沿着时间而变化，则仅使用整个数据样本的这种估计可能提供误导性的结论。本研究的主要目的是建立一种估计市场力随时间变化的方法，并建立一个市场力的时间序列指标，使我们能够与传统产业组织研究的主要研究课题之一的市场结构指标（如市场份额）进行比较。以美国大豆出口为例进行实证分析。本研究中估计美国出口商市场支配力的方法是剩余需求模型，该模型使我们能够得出市场支配力的程度，并已广泛用于国际市场。为了捕捉市场力的时间变化，滚动窗口回归方法被应用于模型，这是一种方法，使用总数据的子样本，通过用固定窗口移动起点和终点来重复回归。在每次滚动估计中引入剩余需求弹性参数，计算出市场力的时间序列指标。使用GMM-nonIV和窗口大小为30的剩余需求模型滚动回归的估计结果表明，美国在1995年之前对进口商具有一定的市场势力，但从20世纪90年代末到2010年，市场势力越来越小。它还表明，从1996年到2010年，美国对中国几乎没有市场力量。另一方面，特别是从20世纪90年代后期开始，美国对墨西哥和日本的市场支配力不断增加，尽管对日本的影响程度大于对墨西哥的影响程度。利用市场力估计指数和已公布的市场份额指数，分析了市场结构与绩效的关系。分析表明，美国大豆出口商对进口商平均市场势力的变化与美国在世界大豆出口中的市场份额下降和中国进口量增加导致的进口商集中度上升相对应。另外，美国对大豆进口依赖度较高的墨西哥和日本的市场支配力指数，可能与美国粮食出口产业的市场结构变化相对应。
As the development of methodology in new empirical industrial organization (NEIO), there have been increasing number of studies that estimate market power of sellers and/or buyers in various kinds of agricultural supply chains. Many of them, however, do not capture time variation of market power during the sample periods, even though they use long time series data. If the degree of market power actually changes along the time, such an estimation that uses only whole sample of the data may provide a misleading conclusion. The main objective of this study is to establish a way of estimating time variation of market power and making a time series index of it. Such an index enables us to make a comparison with indices of market structure, such as market share, which has been one of the main research topics of traditional industrial organization studies. Empirical analysis is conducted using the case of the U.S. soybean exports. The methodology employed in this study to estimate market power of the U.S. exporters is residual demand model, which enables us to derive the degree of market power and has widely been used in the context of international markets. To capture time variation of the market power, rolling window regression method is applied to the model, which is a methodology that repeats regressions using subsamples of total data by shifting the start and end points with a fixed window. Using the parameter of residual demand elasticity in each rolling estimation, a time series index of market power is calculated. The estimation results of rolling regressions of residual demand model using GMM-nonIV and the window size of 30 show that the U.S. had market power over importers to some extent until 1995, but had less and little power from the late 1990s to 2010. It also showed that the U.S. had almost no market power over China from 1996 to 2010. On the other hand, especially from the late 1990s, the U.S. had increasing market power over Mexico and Japan, although the extent was larger to Japan than to Mexico. Using the estimated index of market power and published index of market shares, then the relation between market structure and performance was analyzed. The analysis indicates that the changes in market power of the U.S. soybean exporters to importers average correspond to the decrease of the U.S. market share in the world soybean exports and to the increase of importers concentration due to the increase of China’s imports. It is also pointed out that indices of the U.S. market power over Mexico and Japan who depend soybean imports heavily on the U.S. may correspond to the changes in the market structure of the U.S. grain exporting industry.
影响因子：
2.5
作者：
通讯作者：
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捕捉不对称价格传导的变化：使用蓝鳍金枪鱼案例研究的滚动窗口 TAR 估算
DOI：
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发表时间：
2011
期刊：
Journal of International Fisheries
影响因子：
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作者：
Toru Nakajima;Takahiro Matsui;Yutaro Sakai;Nobuyuki Yagi
通讯作者：
Nobuyuki Yagi