Emi Nakamura, nagrada za utemeljen dvom v neokeynesianske modele

Letošnja prestižna nagrada John Bates Clark medal za ekonomiste izpod 40. leta je po 26 letih spet šla v roke makroenomistom (zadnji makroekonomist, ki jo je dobil, je bil leta 1993 Larry Summers, sicer nečak nobelovca Paula Samuelsona). Natančneje, šla je v roke makroekonomistki Emi Nakamura iz progresivne univerze Berkeley. Nakamuro uvrščajo v neokeynesiansko šolo. Za tiste, ki so vam te smeri v ekonomiji tuje, naj samo pojasnim, da neokeynesianska šola nima nič s Keynesom, pač pa gre za neomonetaristično šolo, od katere se razlikuje v tem, da dopušča “lepljive” cene in plače (da se cene in plače ne prilagodijo takoj, ko pride do krize) in da zato dopušča možnost kratkoročnega odstopanja zaposlenosti od polne zaposlenosti.

No, ker imajo vsake oči svojega malarja, bodo nekateri to nagrado Nakamuri tolmačili kot priznanje za izgradnjo neokeynesianske šole, drugi pa bodo v tem videli nagrado za utemeljen dvom v postulate neokeynesianske šole. Nakamura (in njen soavtor in mož Jon Steinsson) sta namreč nanizala cel kup raziskav, ki so pokazali, da nekatere ključne predpostavke in pogledi neokeynesianske šole empirično niso relevantni ali imajo večji ali drugačen vpliv od predpostavljenega. Nakamura in Steinsson sta tudi naredila empirično raziskavo učinkov fiskalnega stimulusa in za vojaške izdatke denimo pokazala, da je multiplikator izdatkov okrog 1.5 (vsak javni dolar za vojsko ustvari dodatno še pol dolarja dodatnega outputa v zasebnem sektorju).

Ključna lastnost Nakamure pa se zdi, da ni dogmatična, ampak da marljivo zbira kamenčke v mozaiku resnice in da išče metodološke pristope, ki bi ekonomistom omogočili bolj trdne sklepe o tem, kar kažejo podatki.

Spodaj je nekaj odstavkov iz dobrega komentarja Noaha Smitha v Bloombergu o opusu Emi Nakamura. Spada pa njegov tekst v tisto drugo skupino pogledov.

But despite her status as one of the leading lights of New Keynesian economics, Nakamura has spent much of her career challenging the idea. In a recent paper with Steinsson, she showed that interest rate cuts tend to boost expectations of future growth without raising expected inflation much — in contradiction of what standard New Keynesian models (and the intuition of many macroeconomists) would predict. In another paper the two economists questioned the assumption of many New Keynesian models that inflation causes as much harm to the economy as unemployment.

The biggest failure of standard New Keynesian models is that they assume a central bank always has the ability to fight recessions by lowering interest rates. The recent Great Recession exposed the limits of this tool because nominal interest rates can’t go much below zero. Some economists have suggested that in lieu of cutting rates, central banks could use forward guidance — that is, promising to keep rates lower for longer even after the recession ends — to much the same effect. But together with Alisdair McKay and Steinsson, Nakamura showed that theories that predict big effects for forward guidance are highly unrealistic.

If interest rate cuts and forward guidance fail, what can be done to fight recessions? One of the most potent weapons might be fiscal stimulus via government spending programs. In 2011, as the U.S. was struggling to get its economy growing again and politicians were debating whether to enact deep budget cuts, Nakamura and Steinsson came out with the first version of a paper measuring the effects of stimulus. Looking at differences in military procurement across states, the economists measured how changes in local government spending boosted local economies. Their conclusion — that each dollar of government spending stimulated about 50 cents of additional private economic activity — was influential both within the economics profession and outside of it.

But macroeconomics being the inexact science that it is, even very well-done papers like Nakamura and Steinsson’s can’t prove beyond a shadow of a doubt that stimulus works. That’s why macroeconomists often have to act like detectives, gathering shreds of statistical evidence from a variety of sources and aggregating them into a coherent picture. In a recent survey paper, Nakamura and Steinsson discuss statistical approaches that macroeconomists can use to be more confident that the correlations they observe really represent causation.

Vir: Noah Smith, Bloomberg Opinion

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