So kakšne koristi od makroekonomije?

Niti ne gre (več) za heretično vprašanje, saj teh nesramnih vprašanj ne postavljajo samo “outsiderji”, ampak je samospraševanje vesti že zdavnaj zajelo tudi same makroekonomiste. In že zdavnaj ne gre več samo zato, ali je naša stroka kaj vredna, če ne znamo vsaj približno napovedovati poslovnih ciklov (kriz) in če ne znamo najti – konsenzualno – univerzalnega recepta za izhod iz sedanje krize, pač pa gre za to, ali so naši (makro) modeli, sploh kaj vredni, če pa temeljijo na fantazijskih predpostavkah, na osnovi katerih se vam bo vsak fizik ali poslovnež režal v obraz.

No, odgovor je odvisen, za kakšno vrsto makroekonomije gre in ali vam služi zgolj kot igračka za larpurlarstistično nadmudrivanje v akademskem peskovniku ali pa jo jemljete resno za napovedovanje in je od preciznosti napovedi odvisna vaša služba oziroma denarnica. Noah Smith je v petek napisal dober članek, v katerem je makroekonomijo po uporabnosti razdelil v štiri skupine. Prva je kavarniška makro, ki ne temelji na realnih osnovah, predvsem na ideološko pogojenih pogledih na svet (gre predvsem za kavarniške “avstrijance”, privržence Hayeka in von Misesa), druga je finančna makro, ki uporablja bolj ali manj sofisticirane modele in veliko dozo “uganjanja z oslinjenim prstom, uperjenim v zrak” za napovedovanje makroekonomskih agregatov in posledično njihovega vpliva na cene finančnih instrumentov.

Tretja je akademska makro, ki zadnja tri desetletja po Lucasovi makroekonomski kontrarevoluciji temelji predvsem na simplističnih dinamičnih stohastičnih modelih splošnega ravnotežja (DSGE), ki – no ja, zaradi utemeljenosti na fantazijskih predpostavkah – nimajo prav nobene napovedne ali druge uporabne vrednosti v realnem svetu. In četrta je “centralnobančna” makro, se pravi eklektična makro, ki kombinira analizo podatkov in modele ter se trudi na njihovi osnovi in na podlagi osebne presoje dobiti relevantne napovedi makro agregatov. Ker pač centralne banke delajo ekonomsko politiko in se ne morejo prepustiti fantazijskemu svetu akademskih peskovnikov. Po Smithovem mnenju imamo torej opravka z (1) ideološko, (2) ugankarsko, (3) fantazijsko in (4) presojevalno makroekonomijo.

The first is what I call “coffee-house macro,” and it’s what you hear in a lot of casual discussions. It often revolves around the ideas of dead sages — Friedrich Hayek, Hyman Minsky and John Maynard Keynes. It doesn’t involve formal models, but it does usually contain a hefty dose of political ideology.

The second is finance macro. This consists of private-sector economists and consultants who try to read the tea leaves on interest rates, unemployment, inflation and other indicators in order to predict the future of asset prices (usually bond prices). It mostly uses simple math, though advanced forecasting models are sometimes employed. It always includes a hefty dose of personal guesswork.

The third is academic macro. This traditionally involves professors making toy models of the economy — since the early ’80s, these have almost exclusively been DSGE models (if you must ask, DSGE stands for dynamic stochastic general equilibrium). Though academics soberly insist that the models describe the deep structure of the economy, based on the behavior of individual consumers and businesses, most people outside the discipline who take one look at these models immediately think they’re kind of a joke. They contain so many unrealistic assumptions that they probably have little chance of capturing reality. Their forecasting performance is abysmal. Some of their core elements are clearly broken. Any rigorous statistical tests tend to reject these models instantly, because they always include a hefty dose of fantasy.

The fourth type I call Fed macro. The Federal Reserve uses an eclectic approach, involving both data and models. Sometimes the models are of the DSGE type, sometimes not. Fed macro involves taking data from many different sources, instead of the few familiar numbers like unemployment and inflation, and analyzing the information in a bunch of different ways. And it inevitably contains a hefty dose of judgment, because the Fed is responsible for making policy.

How can there be four very different activities that all go by the same name, and all claim to study and understand the same phenomena? My view is that academic macro has basically failed the other three.

Because academic macro models are so out of touch with reality, people in causal coffee-house discussions can’t refer to academic research to help make their points. Instead, they have to turn back to the old masters, who if vague and wordy were at least describing a world that had some passing resemblance to the economy we observe in our daily lives.

And because academic macro is so useless for forecasting — including predicting the results of policy changes — the financial industry can’t use it for practical purposes. I’ve talked to dozens of people in finance about why they don’t use DSGE models, and some have indeed tried to use them — but they always dropped the models after poor performance.

Vir: Noah Smith

Brad DeLong (Berkeley), ki je sicer simpatetičen s Smithom, se z njim ne strinja povsem. Je bolj kritičen do finančne makro, k štirim skupinam pa bi dodal še politekonomsko makroekonomijo. S slednjo misli intelektualni okvir ekonomske politike po 2010, ki ga “krasi” popolni dizaster na strani (varčevalne) fiskalne politike, mešan uspeh regulatorne politike in relativen uspeh monetarne politike. Predvsem pa je DeLong  ubijalski do akademske makro in kritičen do bistrosti teh ekonomistov:

If you insist on trying to understand business cycles by requiring a single consumption Euler equation (rather than, say, risk-averse rich 70-somethings with short horizons; myopic middle-class 40-somethings, and the liquidity constrained); if you insist on trying to understand business cycles by requiring that firms engage in Calvo pricing; If you insist on trying to understand business cycles by requiring rational expectations (rather than anchored, adaptive, extrapolative, perfect-foresight, and Panglossian)–well, then you really aren’t very bright at all, are you?

Vir: Brad DeLong

Kaj torej narediti z makroekonomijo, da bo bolj uporabna za reševanje problemov vsakdanjega svete? Smith navaja Justina Wolfersa in njegovo napoved, da so DSGE modeli “out”:

But that’s just the beginning — far deeper changes may be in the offing. Wolfers suggested abandoning DSGE models, saying that they “haven’t worked.” That he said this at a conference honoring Blanchard, who was an important DSGE modeling pioneer, is a sign that the winds have shifted.

In place of the typical DSGE fare, Wolfers suggests that the new macroeconomics will focus on empirics and falsification — in other words, looking at reality instead of making highly imaginative assumptions about it. He also says that macro will be fertilized by other disciplines, such as psychology and sociology, and will incorporate elements of behavioral economics.

Na drugi strani pa je Roger Farmer, prav tako z Berkeleya, ki je sicer tudi zelo kričen do DSGE modelov – vendar le do standardnih DSGE modelov, ki predpostavljajo enotno (splošno) ravnotežje, ki naj bi bilo hkrati tudi optimalno ravnotežje (ni dolgotrajne nezaposlenosti). Farmer je sicer razvil novo linijo DSGE modelov, ki omogočajo multipla ravnotežja in hrati še nezaposlenost, pri čemer lahko ravnotežje z veliko brezposelnostjo traja v nedogled. In Farmer je seveda mnenja, da je prihodnost makroekonomije v smeri takšnih – njegovih! – DSGE modelov z možnimi tisočerimi ravnotežji in poljubno stopnjo brezposelnosti. Farmer se zato zavzema za formalizirano (matematično) makroekonomijo, vendar pa priporoča pragmatičen in aplikativen pristop Alfreda Marshalla (najboljšega ekonomista pred Keynesom in Keynesovega učitelja in predhodnika na Cambridgeu) k uporabi matematike:

  1. Use mathematics as shorthand language, rather than as an engine of inquiry. 
  2. Keep to them till you have done. 
  3. Translate into English. 
  4. Then illustrate by examples that are important in real life. 
  5. Burn the mathematics.
  6. If you can’t succeed in 4, burn 3.

Vir: Roger Farmer

Nisem prepričan, da bo Farmerjeva linija tukaj zmagala. Ne zato, ker ne bi imel dobre ideje, pač pa zato, ker gre za ideološko nevzdržno idejo. Akademiki, ki se igrajo v peskovniku z DSGE modeli, pač religiozno verjamejo v brezmadežnost prostega trga, popolne konkurence, racionalnosti posameznikov in njihove nezmotljivosti ter da vsak šok gospodarstvo (po določenem prilagajanju) povrne nazaj v optimalno ravnotežje. Kako lahko na osnovi takšnih predpostavk trezno razmišljaš o realnem, nepopolnem svetu?!

Smith je optimističen in pravi, da bo najbrž prišlo do tega, da bodo makroekonomisti zavrgli DSGE in 30 let tavanja v svetu, ki ne obstaja, ter se soočili z realnimi problemi. To pa pomeni nove modele, ki bodo upoštevali obnašanje posameznikov in podjetij in ki bodo temeljili tudi na psihologiji in sociologiji ter ekonomiki obnašanja. Namesto dosedanjih fantazijskih mikrofundiranih modelov naj bi dobili nove z “makro fokusiranimi mikro osnovami“:

Economists now realize that consumers and businesses behave in ways that are much more complicated and difficult to understand. So there has been increased interest in what’s called “macro-focused micro” — studies of businesses, competition, markets and individual behavior that have relevance for macro even though they weren’t traditionally included in the field. Examples of this would include studies of business dynamism, price adjustment, financial bubbles and differences between workers.

Let’s hope more and more macroeconomists focus on these things, instead of trying to make big, grandiose, but ultimately vacuous models of booms and recessions. When we understand the pieces of the economy better, we’ll have a much better chance of grasping the whole.

Vir: Noah Smith

Toda če je Smith optimističen, je DeLong bolj previden:

I am not sure. Macroeconomics needs, desperately, better and real behavioral microfoundations at the sector and the market level. But it also needs much better approaches to aggregation–to understanding how macroeconomic phenomena emerge out of real microfoundations.

Tudi jaz nisem prav prepričan v to. Dvomim, da obstaja en univerzalen model, ki lahko pojasnjuje vse situacije in da je dinamika med danes in jutri odvisna zgolj od obrestne mere oziroma sploh, da je gospodarska gibanja mogoče napovedovati (“če bi le lahko dovolj dobro poznali obnašanje posameznikov” in “če bi le imeli dovolj zmogljive računalnike,” da bi vsa te individualna obnašanja agregirali v makro gibanja). Ker sem pragmatik in neideološki, mi je še najbližje pragmatični in eklektični pristop centralnih bank. Treba je pač pogledati, kaj kažejo podatki in čim bolj ideološko neobremenjeno razumeti, kaj gibanja v podatkih resnično pomenijo. Ob tem lahko uporabljamo obstoječa analitska orodja, ki so se že izkazala kot dobro delujoča (ena v teh, druga v drugih okoliščinah) in jih med seboj kombiniramo. Predvsem pa moramo biti odprte glave in biti sposobni se odpovedati našemu razumevanju situacije, če se informacije o realnem svetu, o gospodarski dinamiki spremenijo. Na koncu pa še vedno moramo sami odločiti na podlagi “feelinga” in naše presoje konkretne situacije, namesto da bi slepo sledili modelu ali enostavnim pravilom.

Torej pragmatizem, eklektičnost, fleksibilnost v glavah, prilagodljivost ter osebna presoja.

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