在全球化的今天，國人對外投資對國內經濟的衝擊，在過去二十年中受到許多政治、媒體的關注，國內外學者對這個議題的研究也甚多。學者們研究多著眼於對外投資對國內投資、就業、貿易、工資等重要議題的影響。儘管研究立場多半假設國人對外投資對國內經濟的負面影響，日本及歐美經驗卻提供許多反證。本文以總體經濟的角度，以臺灣為例，利用1981-2005年間的年資料及季資料，應用時間數列資料與迴歸方法，直接探討國人對外投資對國內產出的影響。結果指出對外投資與國內產出間的正向關聯。季資料的Granger因果鑑定更進一步指出由對外投資至國內產出的正向因果關聯。

The magnitude and the rate of growth of outward investment from advanced to emerging economies have raised concerns among policymakers and economists around the globe. The concern is that capital outflows might lead to a reduction in domestic aggregate output and employment, place downward pressures on wages, especially for unskilled labor, or/and lower the rate of domestic capital deepening. These concerns threaten to induce policy change that might limit investment going abroad. However, counter evidence of beneficial effects of outward investment on technological advancement have also been established in the literature. This raises the general question this study will address: what is the nature of the economic process between outward investment and economic performance. The research interests here focus on empirically investigating, using time series data, the nature of the relationship between outward investment and productive capacity, i.e. GDP, for the home economy that provides outward investment. Contrast to the conventional belief, the econometric results indicate persistent positive lagged effects of outward investment on GDP growth despite the downward pressure on domestic employment imposed by outward investment. These results are robust to various model specification and estimation methods for both annual and quarterly data. Adopting the concept of Granger causality, the results further indicate the causal relationship from outward investment to GDP for the case of Taiwan from 1981 to 2005. These findings challenge the negative perceptions upon which conservative policies discouraging outward investment are based, and call for future research focusing on how these positive effects of outward investment on GDP are realized in the home economy.