中文摘要
美元在全球贸易中的主导地位是否已使货币政策失效？一种新兴观点认为，如果一国以美元为其出口商品计价，汇率便无法稳定经济活动，因为经典的支出转换渠道会受到抑制。这一观点建立在出口价格以美元计价且具有黏性的前提之上，从而切断了出口需求与货币贬值之间的联系。然而，数据并不支持这一假设：以美元计价的商品往往价格更加灵活，且具有更高的替代弹性。本文提出一个采用更现实假设的模型，结果表明即使采用美元计价，通过放松货币政策使本币贬值，仍能显著促进出口和经济活动。任何扩张所面临的限制并非需求，而是供给能力。本文还表明，汇率向美元价格的低传递并不能说明价格具有黏性。当需求弹性较高时，即使价格灵活，价格对汇率变动的反应也很小：低传递是一种均衡结果，而非名义摩擦的证据。
Abstract
Abstract Has the dominance of the dollar in global trade rendered monetary policy ineffective? An emerging view contends that if a country invoices its exports in dollars, exchange rates cannot stabilize economic activity, as the classical expenditure-switching channel is muted. This view rests on the premise that export prices are sticky in dollars, breaking the link between export demand and depreciations. But this assumption is not borne out by the data: goods priced in dollars tend to have more flexible prices, along with higher elasticities of substitution. We propose a model with more realistic assumptions and show that even with dollar pricing, depreciating the currency by loosening monetary policy can still boost exports and activity materially. The limit to any expansion is not demand, but supply capacity. We also show that low exchange rate pass-through to dollar prices is not informative about price stickiness. The price response to exchange rates is small when demand elasticities are high, even with flexible prices: low pass-through is an equilibrium result, not evidence of a nominal friction.