質疑耶倫和美聯儲的五個理由

While I do not believe the Federal Reserve made a serious mistake on Wednesday in raising rates, I believe that the “preemption of inflation based on the Phillips curve” paradigm within which it is operating is highly problematic. Much better would be a “shoot only when you see the whites of the eyes of inflation” paradigm of the kind I have advocated for the last several years.

雖然我不認爲美聯儲(Fed)上週三加息犯了嚴重錯誤，但我相信，美聯儲運行的框架——“基於菲利普斯曲線(Phillips curve)搶先狙擊通脹”的策略很有問題。更好的選擇是我在過去幾年一直倡導的策略：“只在看到通脹的確鑿證據時纔開槍”。

Such a paradigm would be more credible, more likely to result in the Fed’s satisfying its dual mandate, reduce the risk of recession and increase the economy’s resilience when recession comes.

後一種策略更可靠，更有可能讓美聯儲完成其雙重任務——降低出現經濟衰退的風險，並增強美國經濟在衰退到來時的韌性。

Many of my friends have recently issued a statement asserting that the Fed should change its inflation target. I suspect, for reasons I will write about in the next few days, that moving away from inflation targeting to something like nominal gross domestic product level targeting would be a better idea. But I believe this issue is logically subsequent to the question of how policy should be made in the near term with the given 2 per cent inflation target.

我的許多朋友最近聯合發表了一份聲明，堅稱美聯儲應改變其通脹目標。我覺得（原因我將在近期再寫），從以通脹爲目標轉向如以名義國內生產總值(GDP)爲目標，是個更好的主意。但我認爲，這一問題邏輯上應排在如下另一問題之後：在通脹目標被設爲2%的情況下，短期政策應如何制定。

Five points frame my doubts about the current approach.

有5點理由支撐我對當前加息策略的質疑。

First, The Fed is not credible with the markets at this point. Its dots plots predict four rate increases over the next 18 months compared with the markets’ expectation of less than two. Table 1 shows the Fed has been highly unrealistic in its forecasts for several years now

首先，眼下美聯儲在市場眼中並不可信。美聯儲的“點陣圖”預計未來18個月將加息4次，相比之下，市場的預期爲不超過兩次。從表一可以看出，美聯儲的預測已有好幾年極度脫離實際。

There are some caveats in comparing market and Fed forecasts. Fed chair Janet Yellen is not necessarily the median dot but has disproportionate influence. Additionally, the dots refer to the modal (most likely) rather than the average future scenario. Both those factors might tend to make the Fed forecast overstated, if Ms Yellen is more dovish than the Fed as a whole. But, on the other hand, market forecasts contain term premiums that are on average positive, implying that market expectations for Fed policy should also be biased to the upside. In sum, there is no rationalising away the protracted pattern of Fed forecasting errors except to doubt the models on which the Fed is relying.

比較市場的預測和美聯儲的預測時應注意一些事項。美聯儲主席珍妮特?耶倫(Janet Yellen)未必就是中值點，但她擁有其他人不可比擬的影響力。此外，點陣圖顯示的是衆數（最有可能的）、而非平均數的未來場景。如果耶倫比美聯儲整體更鴿派的話，這兩個因素都可能傾向於使美聯儲的預測偏高。但另一方面，市場預期包含通常爲正值的期限溢價，這意味着市場對美聯儲政策的預期也應偏高。總之，除了質疑美聯儲依賴的模型，否則美聯儲持續的預測失誤講不通。

The truth is that markets do not share the Fed’s view that inflation acceleration is a major risk. Indeed, they do not believe the Fed will attain its 2 percent inflation target for a long time to come. Table 2 shows than neither inflation indexed bonds nor the swap market expect the Fed to hit its 2 per cent personal consumption expenditure (PCE) inflation goal in the foreseeable future.

事實上，市場並不認同美聯儲的如下觀點：通脹加速是一項重大風險。實際上，市場認爲美聯儲在未來很長一段時間都不會實現2%的通脹目標。表二顯示出，通脹指數化債券和互換市場都預期，在可預見的未來，美聯儲將不會實現2%的個人消費支出(PCE)通脹目標。

If the Fed were equally behind the curve with respect to rising inflation there would be hysteria among the commentariat. They would be proclaiming that the Fed has to move decisively so as not to be behind the curve. Why should there not be concern about disbelieved forecasts of actions that if taken would push inflation further below target than current forecasts?

如果美聯儲在加息上同樣進度落後，那評論圈將炸開鍋。他們將宣稱，美聯儲必須果斷行動，以跟上進度。預測中的行動如果付諸實施，將把通脹推至進一步低於目前預測的水平，這些受到外界懷疑的行動預測，爲什麼沒有引發關切？

Second, the Fed regularly proclaims that it has a symmetric commitment to its 2 per cent inflation target. Recoveries do not last forever and when recession comes inflation declines. So why would the Fed want to be projecting only 2 per cent inflation entering the 11th year of recovery with a jobless rate clearly below their estimate of the non-accelerating inflation rate of unemployment (Nairu). Such a prediction is coming after a full decade of sub-target inflation. As shown in the graph below, the PCE core price level is a full 4.3 per cent below where it would be had it risen by the Fed’s target amount over the past decade.

其次，美聯儲經常宣稱，其對2%通脹目標的承諾是“對稱”的。復甦不會永遠持續，而當衰退到來時，通脹將回落。那麼，爲什麼美聯儲要預測通脹在復甦的第11個年頭只有2%，同時失業率顯然低於他們估算的非加速通脹的失業率(Nairu)。在做出這一預測之前，通脹有整整10年未達到目標。如圖所示，個人消費支出核心價格水平，比按照過去10年美聯儲的目標值本應升至的水平低了整整4.3%。

Accordingly, policy should be set with a view to achieving modestly above-target inflation, perhaps 2.3 or even 2.5 per cent, during a boom with the expectation that it will decline during the next recession. A higher inflation target would entail easier policy than is now envisioned.

因此，制定政策時應確立如下目標：在繁榮時期實現適度高於目標的通貨膨脹，或許是2.3%，甚至2.5%，因爲預期通脹會在下一次衰退時下降。而更高的通脹目標將需要比現在預想的更寬鬆的政策。

Third, pre-emptive attacks on inflation, like pre-emptive attacks on countries, depend on the ability to judge threats accurately. The truth is we have little ability to judge when inflation will accelerate in a major way. The Phillips curve is at most barely present in data for the last 25 years. And as Staiger, Stock and Watson demonstrated years ago the Nairu, assuming such a thing exists, can only be estimated with extreme imprecision.

第三，對通貨膨脹發動先發制人的打擊，就像對國家發動先發制人的打擊一樣，取決於準確判斷威脅的能力。但實際上，我們幾乎沒有能力判斷通脹何時將大幅加速。菲利普斯曲線在過去25年的數據裏幾乎不體現。且正像施泰格(Staiger)、施托克(Stock)和沃森(Watson)數年前所證明的，對非加速通貨膨脹失業率——假設其存在——只能作出極度不精確的估測。

At some points these might seem like theoretical arguments. But in recent months both overall and core inflation have come down along with market and survey measures of inflation expectations. The most widely followed inflation measure, the consumer price index, has decelerated from 2.5 per cent inflation in January to 1.9 per cent now. Accordingly, inflation expectations have fallen 0.2-0.3 per cent. This behaviour is contrary to all the Fed staff models.

某些時候這些可能看上去只是理論上的理由。但近幾個月來，整體通脹率和核心通脹率雙雙下降，通脹預期的市場和調查指標也是如此。居民消費價格指數(CPI)這一受到最普遍關注的通脹指標，今年1月份實現2.5%的通脹，現在降至1.9%。相應地，通脹預期也下降了0.2到0.3個百分點。這一走勢與所有美聯儲成員模型相反。

With inflation and inflation expectations below target and declining there would be little case for pre-emption even if inflation above target was a serious problem. But, as we have seen, there are strong reasons for thinking that the Fed should to be consistent with its mandate and let inflation rise above 2 per cent.

由於通貨膨脹和通脹預期低於目標且不斷下降，即使通脹高於目標是個嚴重的問題，也沒有理由對通脹發起先發制人的打擊。但正如我們所見，有充分理由認爲，美聯儲應一以貫之地執行其任務，讓通脹升高到2%以上。

Fourth, as I have stressed in my writings on secular stagnation and in arecent conversation with David Wessel, there is good reason to believe that a given level of rates is much less expansionary than it used to be given the structural forces operating to raise saving propensities and reduce investment propensities.

第四，正如我之前在討論長期停滯的文章中，以及與戴維?韋塞爾(David Wessel)最近一次交談中所強調的，考慮到能夠提高儲蓄傾向、減少投資傾向的結構性因素在發揮作用，有充分理由認爲，一個給定的利率水平遠不如曾經那樣具有擴張性。

I am not sure that a 2 per cent funds rate is especially expansionary in the current environment. And I am confident that if the Fed errs and tips the economy into recession the consequences will be very serious given that the zero lower bound on interest rates or perhaps a slightly negative rate will not allow the normal countercyclical response. This, too, counsels a bias towards expansion.

我不確定在目前環境下，2%的聯邦基金利率算不算特別具有擴張性。而且我確信，如果美聯儲犯錯導致經濟陷入衰退，後果將是非常嚴重的，因爲利率的零下限或輕微的負利率都無法爲正常的反週期應對提供空間。基於這一點，也應該讓聯邦基金利率偏向擴張性。

Fifth, a “whites of their eyes” paradigm does not require the Fed to abandon its connection to price stability. It simply needs to assert that its objective is to assure that inflation averages 2 per cent over long periods. Then, it needs to acknowledge that while inflation is persistent, it is very difficult to forecast and signal that it will focus on inflation and inflation expectations data rather than measures of output and employment in forecasting inflation.

第五，“看到通脹的確鑿證據時纔開槍”模式，不要求美聯儲放棄與價格穩定的關聯。美聯儲只需堅持，其目標是確保通脹的長期均值爲2%。接下來，它需要承認，雖然通脹持續存在，但很難預測通脹，並暗示它在預測通脹時，將把重點放在通脹以及通脹預期數據，而不是產出及就業指標上。

With these principles internalised, the Fed would lower its interest rate forecasts to those of the market and be more credible. It would allow inflation to get closer to target and give employment and output more room to run.

納入這些原則後，美聯儲會把其利率預測降至與市場預測持平，會變得更可信。它會容許通脹處於離目標更近的水平，併爲就業和產出提供更多空間。