Forward guidance
前瞻性指引
“Forward guidance” refers to central bank communication about the likely future path of its policy rate. As I understand it, central banks have long (since 1994) communicated its near-term expectations for policy rates, presumably to reinforce its current policy rate target.
However, “forward guidance” later became recognised as a formal tool of monetary policy. I understand this followed the 2008 financial crisis, during which monetary policy became subject to the zero lower bound (“ZLB”). Central banks began communicating expectations beyond the “near term”; for example, that the policy rate would remain as they are until unemployment (or some other macroeconomic metric) reached some relevant target.
Whereas earlier forward guidance (so called, “Delphic forward guidance”) merely conveyed expectations, formal forward guidance (so called “Odyssean forward guidance”) came to be viewed as an explicit commitment by the central bank on the future path of policy rates. [Note 1] We can think of Odyssean forward guidance as an alternative to Yield Curve Control (“YCC”). Forward guidance applies only to the policy rate (for lending and borrowing cash among commercial banks), whereas YCC applies to long-yields (on government bonds traded in the bond market). However, if the rational expectations hypothesis holds strictly, the yield curve is the future path of central bank policy rates (holding the term premium constant), and so YCC implies forward guidance. We could perhaps think of forward guidance as a mechanism for implementing YCC.
In practice, forward guidance usually entails specifying some relevant macroeconomic metric as a policy target - e.g., unemployment or GDP growth. With YCC, the relevant target is the long-yield itself; there is no other target. In addition, forward guidance need not be implemented by acquiring any specific security; YCC applies to a specific security (e.g., 3-year government bonds).
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Note 1: The distinction between Delphic and Odyssean forward guidance is due to Charles Evans and his colleagues (at Evans et al 2012, “Macroeconomic Effects of FOMC Forward Guidance).
“前瞻性指引”是指央行就其政策利率未来可能走向的沟通。据我所知，中央银行长期以来（自1994年以来）一直在传达其对政策利率的近期预期，大概是为了加强其当前的政策利率目标。
然而，“前瞻性指引”后来被公认为货币政策的正式工具。据我了解，这是在2008年金融危机之后，在此期间货币政策受到零下限（“ZLB”）的制约。央行开始传达“近期”以外的预期；例如，即政策利率将保持不变，直到失业率（或其他宏观经济指标）达到某个相关目标。
早期的前瞻性指引（所谓的“德尔菲式（Delphic）的前瞻指引”）仅仅传达了预期，而正式的前瞻性指引（所谓的“奥德修斯式（Odysseus）前瞻性指引”）则成为被视为央行对未来政策利率走向的明确承诺。[注1] 我们可以将奥德修斯式前瞻性指引视为收益率曲线控制（“YCC”）的替代方案。前瞻性指引仅适用于政策利率（对于商业银行之间的现金借贷），而YCC使用于长期收益率（债券市场上交易的政府债券）。但是，如果理性预期假说严格成立，收益率曲线就是央行政策利率的未来途径（保持期限益价不变），因此YCC意味着前瞻性指引。我们或许可以将前瞻性指引视为实施YCC的一种机制。
在实践中，前瞻想指引通常需要指定一些相关的宏观经济指标作为政策目标 - 例如失业率或GDP增长。对于YCC，相关目标就是长期收益率本身；没有其他目标。此外，前瞻性指引不需要通过收购任何特定证券来实施而YCC使用于特定证券（例如3年期政府债券）。
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注1: 德尔菲式与奥德修斯式前瞻想指引之间的区别归功于Charles Evans 及其同事（Evans等人2012《FOMC前瞻性指引的宏观经济影响》）。