Michael Bordo「通念を疑う〜金融危機を伴う景気後退の後に続くのは弱々しい景気回復か？〜」
●Michael Bordo, “Financial Recessions Don't Lead to Weak Recoveries”（Wall Street Journal, September 27, 2012）
Historinhas経由。
金融危機を伴う景気循環の方が金融危機を伴わないそれよりもプラッキングモデルの当てはまりがいい（＝景気後退の度合いが深刻なほどその後に続く景気回復は力強い）、という発見は興味深い。
There's a belief among policy makers that serious recessions associated with financial crises are necessarily followed by slow recoveries—like the one we've experienced since mid-2009. But this widespread belief is mistaken. To the contrary, U.S. business cycles going back more than a century show that deep recessions accompanied by financial crises are almost always followed by rapid recoveries.
（金融危機を伴った深刻な景気後退の後には必然的に緩やかな景気回復が続く−まさに2009年半ば以降に我々が経験してきているように−、といった信念が政策当局者の間で広く抱かれているが、この信念は間違いである。事実はその反対であって、過去1世紀以上にわたるアメリカ経済の経験に照らすと、金融危機を伴う深刻な景気後退の後には大抵の場合急速な景気回復が生じることが示されている。）The mistaken view comes largely from the 2009 book "This Time Is Different," by economists Carmen Reinhart and Kenneth Rogoff, and other studies based on the experience of several countries in recent decades. The problem with these studies is that they lump together countries with diverse institutions, financial structures and economic policies. They also conflate two different measures of speed—how long it takes a country to get back to its previous business-cycle peak, and how fast the economy grows once the recovery has started.
（この誤った信念は2009年に出版されたラインハート＝ロゴフ著『This Time Is Different』（邦訳『国家は破綻する−金融危機の800年』）や過去数十年にわたる各国の経験を検証した一連の研究に大いに支えられているが、これら一連の研究は問題を抱えている。その問題というのは、それぞれに異なる制度や金融システム、経済政策を持つ国々を一緒くたにして論じている点に加えて、景気回復のペース（スピード）を測る2つの異なる指標−生産の水準（実質GDP）が危機以前のピークに戻るまでにどれだけの期間を要するか、景気回復が始まった後に経済がどの程度のペースで成長するか−を区別することなくごっちゃにしている点である。）Milton Friedman had a different way of looking at recoveries from cyclical downturns: the "plucking" model. Friedman imagined the U.S. economy as a string attached to an upward sloping board, with the board representing the underlying long-run growth rate. A recession, in this view, was a downward pluck on the string; the recovery was when the string snapped back. The greater the pluck, the faster the bounce back to trend.
（景気後退の後に続く景気回復の性質に関してミルトン・フリードマンは（現在政策当局者の間で広く抱かれている信念とは）異なった見方−いわゆる「プラッキング」モデル−を提示している。フリードマンのプラッキング・モデルによると、アメリカ経済は右上がりの板−右上がりの板は経済の長期的なトレンド（潜在GDPの推移）を表している−の下面に沿って貼り付けられた糸*1に見立てられることになる*2。景気後退は糸が下にぐいっと引っ張られることで生じ、下に引っ張られた糸が再び板の下面（トレンド）に戻るまでの過程が景気回復の局面を表すことになる。糸が下に引っ張られる程度が大きいほど*3糸が再び板の下面（トレンド）に立ち戻る過程は急速なものとなる。）As Friedman wrote in 1964, "A large contraction in output tends to be followed on the average by a large business expansion; a mild contraction, by a mild expansion."
（1964年にフリードマンは次のように書いている。「大規模な生産の落ち込みの後には平均的に見て大規模な生産の回復が生じる傾向にある。また、生産の落ち込みが緩やかな場合にはその後に続く生産の回復は（平均的に見て）緩やかな傾向にある。」）In a recent working paper for the National Bureau of Economic Research, Joseph Haubrich of the Federal Reserve Bank of Cleveland and I examined U.S. business cycles from 1880 to the present. Our study not only confirms Friedman's plucking model but also shows that deep recessions associated with financial crises recover at a faster pace than deep recessions without them.
（つい最近執筆した共著論文で私は1880年から現在までにわたるアメリカの景気循環の検証に乗り出した。その研究の結果として、フリードマンのプラッキング・モデルは現実のデータに適合しており、金融危機を伴う深刻な景気後退と金融危機を伴わない深刻な景気後退とを比べると前者（金融危機を伴う深刻な景気後退）の方がその後に続く景気回復のペースが急速である、という点が明らかとなった。）
We found that recessions that were tied to financial crises and were 1% deeper than average have historically led to growth that is 1.5% stronger than average. This pattern holds even when we account for various measures of financial stress, such as the quality spread between safe U.S. Treasury bonds and BAA corporate bonds and bank loans.
これまでアメリカ経済が経験してきた歴史的なパターンに照らすと現在のアメリカが置かれている状況はむしろ例外ケースであり、2009年7月以降の景気回復のペースがこれまでの歴史的なパターンから予測されるよりも緩やかであった理由は住宅部門の低迷（住宅投資の伸び悩み）にあると考えられ、（過去3年間にわたる金融緩和策は住宅部門の回復を促す上では限定的な効果しか持たなかった点を勘案すると）住宅部門の回復を促すためには（そしてそれに伴って景気回復のペースが加速するよう促すためには）金融緩和策以外の手段が必要になるかもしれない、とのこと。
Thus the slow recovery that we are experiencing from the recession that ended in July 2009 is an exception to the historical pattern. This can largely be attributed to the unprecedented housing bust, a proximate measure of which is the collapse of residential investment, which still is far below its historic pattern during recoveries. Another problem may be uncertainty over changes in fiscal and regulatory policy, or over structural change in the economy.
The legacy of the unprecedented housing bust calls into question whether in the future, expansionary monetary policy could make recoveries more consistent with the depth of recessions. Expansionary monetary policy in the past three years seems to have had only limited traction in stimulating the economy and speeding housing recovery. To catalyze full recovery in housing, we may need policies other than looser monetary policy.
（追記）ちなみに、記事で参照されているワーキングペーパーは以下。
●Michael D. Bordo and Joseph G. Haubrich, “Deep Recessions, Fast Recoveries, and Financial Crises: Evidence from the American Record（pdf）”（NBER Working Paper No. 18194, June 2012）
Our analysis of the data shows that steep expansions tend to follow deep contractions, though this depends heavily on when the recovery is measured. In contrast to much conventional wisdom, the stylized fact that deep contractions breed strong recoveries is particularly true when there is a financial crisis. In fact, on average, it is cycles without a financial crisis that show the weakest relation between contraction depth and recovery strength. For many configurations, the evidence for a robust bounce-back is stronger for cycles with financial crises than those without. The results depend somewhat on the time period, with cycles before the Federal Reserve looking different from cycles after the Second World War.（pp.2）
Regressing growth 4 quarters after the trough against contraction amplitude shows a positive but small and statistically insignificant relationship. The relationship is tighter, and stronger, if we examine more of the recovery, measuring growth out to the duration of the contraction after the trough. Looking out only 4 quarters can give a misleading picture, particularly for longer recessions. Much of the difference is in fact driven by the Great Depression, and it should not be surprising that the drop in output from 1929 to 1933 was not fully reversed by 1934, though the economy came much closer by 1936.
Do financial crises affect the bounceback? The scatterplots in Figure 3 strongly suggest a difference between the recoveries in crisis and noncrisis cycles, but for reasons contrary to the conventional wisdom. In crisis times, strong recoveries follow deep recessions, but outside of a crisis, they do not. The relation is in fact negative, though not statistically significant.（pp.11）
（追々記）M.フリードマンの「プラッキングモデル」については例えば以下を参照のこと。
●tanakahidetomi, 「Pluckingモデルとオーストリア的景気循環論」（Economics Lovers Live Z, 2006年8月9日）
●Milton Friedman, “The "Plucking Model" of Business Fluctuations Revisited（pdf）”（Hoover Institution Working Paper No. E-88-48, December 1988）
●Lars Christensen, “Do you remember Friedman’s “plucking model”?”（The Market Monetarist, October 22, 2011）
●Marcus Nunes, ““Plucking””（Historinhas, October 23, 2011）
●John B. Taylor, “More Evidence on What Is Holding the Economy Back”（Economics One, May 13, 2012）
●Marcus Nunes, “What´s “cramping” the pluck?”（Historinhas, May 13, 2012）（↑のJohn B. Taylorのエントリーに対する反応）
（さらに追記；2012年10月16日）ラインハート＝ロゴフによる反論。
●Carmen M. Reinhart and Kenneth S. Rogoff, “This Time is Different, Again? The United States Five Years After the Onset of Subprime（pdf）”
以下も参照。
●M.C.K., “Is the slow recovery unusual?”（Free exchange, October 15, 2012）
