技術優勢和本國市場效果：卜瓦松準最大概似估計模型

Technology Advantage and Home-Market Effect: A Poisson QuasiMaximum Likelihood Estimation

根據新貿易理論的本國市場效果（horne-rnarket effects），自由貿易會使大國擴大其市場占有率，對小國則造成製造業萎縮，極端情況則整個產業消失。本文旨在分析和檢視技術優勢如何影響所謂的本國市場效果。技術效果可以分為兩個層次：一者為因技術優勢使得成本較低，產出提高的直接效果；其二則是透過貿易後廠商得以存活的間接效果。據此，本文利用引力模型之卡瓦松準最大概似估計來驗證技術優勢對本國市場效果的影響，我們選定11個不同屬性的產業，即傳統勞力密集的紡織成衣業、具經濟規模的運輸機具產業，以及最技術密集的半導體產業等。我們的實證結果發現：（1）不同屬性產業所反映之本國市場效果程度不一；（2） 技術密集產業愈可能出現本國市場效果被抵銷情況，而且直接和間接技術效果均有相同結果；亦即對於技術密集型產業來說，當出口國具有相對技術優勢，將促使該國有更多的出口。

According to the conventional home-market effect, free trade tends to shrink the market share for a small economy with differentiated manufacturing goods, and in the extreme leads to a complete hollowing-out of the industry in a small economy. This paper considers the technology difference between countries using the standard Helpman-Krugman model. We will show that the home-market effect can be offset and even reversed if the smaller economy is characterized by better technology. The effect of a technology advantage is composed of two parts: a direct effect from lower unit costs that lead to a higher output level of each firm, and an indirect effect through a change in terms of which firms survive after trade. Based on theoretical results, we derive the gravity equation to conduct empirical tests on the hypothesis of the home-market effect, and direct and indirect technology effects using the US patent stock of 2002 for eleven industries ranging from the most technology-intensive industry to the most labor-intensive apparel and clothing industry. Empirical results show that the degree of the home-market effect varies from industry to industry. The reversal of the home-market effect is more likely to occur in technology-intensive industries. Consistently, direct and indirect technology effects also occur in the industries with a reversed home-market effect.