Qingyuan Du

Economics Department
Monash University
Melburne, Australia

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NBER Working Papers and Publications

August 2013Roads and the Real Exchange Rate
with Shang-Jin Wei, Peichu Xie: w19291
This paper studies the effect of transport infrastructure on the real exchange rate (RER) and reaches two relatively strong conclusions. First, while the list of robust determinants of the RER is not long, transport infrastructure belongs to that list. Many other potential determinants proposed in the literature, such as net foreign asset position or terms of trade, turn out to be not robust. Second, in terms of economic significance, the infrastructure effect follows closely the well-known Balassa-Samuelson effect and is one of the most important explanatory variables for RER movements, especially in developing countries.
March 2013A Theory of the Competitive Saving Motive
with Shang-Jin Wei: w18911
Motivated by recent empirical work, this paper formalizes a theory of competitive savings - an arms race in household savings for mating competition that is made more fierce by an increase in the male-to-female ratio in the pre-marital cohort. Relative to the empirical work, the theory can clarify a number of important questions: What determines the strength of the savings response by males (or households with a son)? Can women (or households with a daughter) dis-save? What are the conditions under which aggregate savings would go up in response to a higher sex ratio? This theory can potentially help to understand the savings patterns in China, India, Vietnam, Singapore, Hong Kong, and other economies that have experienced a dramatic increase in the pre-marital sex ratio.

Published: Du, Qingyuan & Wei, Shang-Jin, 2013. "A theory of the competitive saving motive," Journal of International Economics, Elsevier, vol. 91(2), pages 275-289. citation courtesy of

February 2011A Darwinian Perspective on "Exchange Rate Undervaluation"
with Shang-Jin Wei: w16788
Though the real exchange rate is a key price for most economies, our understanding of its determinants is still incomplete. This paper studies the implications of status competition in the marriage market for the real exchange rate. In theory, a rise in the sex ratio (increasing relative surplus of men) can generate a decline in the real exchange rate (RER) through both a savings channel and an effective labor supply channel. The effects can be quantitatively large if the biological desire for a marriage partner is strong. Empirically, we show that within China, those regions with a faster increase in the sex ratio also exhibit a faster decline in the RER (the relative price of nontradables). Furthermore, across countries, those with a high sex ratio tend to have a low real exchange rate, ...

Published: Du, Qingyuan & Wei, Shang-Jin, 2016. "A Darwinian perspective on “exchange rate undervaluation”," European Economic Review, Elsevier, vol. 83(C), pages 111-138. citation courtesy of

May 2010A Sexually Unbalanced Model of Current Account Imbalances
with Shang-Jin Wei: w16000
Large savings and current account surpluses by China and other countries are said to be a contributor to the global current account imbalances and possibly to the recent global financial crisis. This paper proposes a theory of excess savings based on a major, albeit insufficiently recognized by macroeconomists, transformation in many of these societies, namely, a steady increase in the surplus of men relative to women. We construct an OLG model with two sexes and a desire to marry. We show conditions under which an intensified competition in the marriage market can induce men to raise their savings rate, and produce a rise in the aggregate savings and current account surplus. This effect is economically significant if the biological desire to have a partner of the opposite sex is strong. A...
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