Wednesday, March 11, 2009

El problema con los economistas

Ya salió un paper explicando porque la mayoría de los economistas no previeron la crisis.

La hipotesis no es nueva:"The economics profession appears to have been unaware of the long build-up to the current worldwide financial crisis and to have significantly underestimated its dimensions once it started to unfold. In our view, this lack of understanding is due to a misallocation of research efforts in economics. We trace the deeper roots of this failure to the profession’s insistence on constructing models that, by design, disregard the key elements driving outcomes in real-world markets. The economics profession has failed in communicating the limitations, weaknesses, and even dangers of its preferred models to the public. This state of affairs makes clear the need for a major reorientation of focus in the research economists undertake, as well as for the establishment of an ethical code that would ask economists to understand and communicate the limitations and potential misuses of their models.......We believe that economics has been trapped in a sub-optimal equilibrium in which much of its research efforts are not directed towards the most prevalent needs of society. Paradoxically self-reinforcing feedback effects within the profession may have led to the dominance of a paradigm that has no solid methodological basis and whose empirical performance is, to say the least, modest. Defining away the most prevalent economic problems of modern economies and failing to communicate the limitations and assumptions of its popular models, the economics profession bears some responsibility for the current crisis. It has failed in its duty to society to provide as much insight as possible into the workings of the economy and in providing warnings about the tools it created. It has also been reluctant to emphasize the limitations of its analysis. We believe that the failure to even envisage the current problems of the worldwide financial system and the inability of standard macro and finance models to provide any insight into ongoing events make a strong case for a major reorientation in these areas and a reconsideration of their basic premises."

Justin Wolfers comenta sobre el paper en el blog de Freakonomics:"The claim is that academic macroeconomists have become mired in a particularly fruitless equilibrium, in which each is engaged in the search for ever-greater levels of formal elegance, at the expense of empirical relevance. There’s definitely something to this.Today’s macroeconomists write for other macroeconomists. If you aren’t using the right tools, you aren’t part of the club."

En otras palabras se convirtió en jueguito de status para ver quien sabe es mas formal, mas elegante matemáticamente. Hay que tener en cuenta que ese jueguito puede tener graves consecuencias para la sociedad (un magister en economía ( y MBA y Phd en estadística) fue el creador de la "formula que mató a Wall Street")

El problema tambien parece que tiene que ver con el "sesgo de publicación":

"The more I look at empirical results, the closer appear the flaws of a data-centric worldview. Data never speak for themselves, and the process of their interpretation is every bit as political as other forms of analysis. But when you analyze data, you focus on the minutae of your dataset, so you're further divorced for the subject matter. You can make all sorts of crazy claims that would never slide if you were forced to present your views in a clear manner in front of a lay-audience remotely familiar with the subject matter.

The problem is that empirical claims are generally accepted or rejected on the basis of statistical tests meeting a certain treshold. But creating such a treshold gives researchers a pole to vault; when they manage to do so, they publish, when they don't, they do not publish. Instead of statistical tests revealing anything about the state of the world, they only reveal what researchers could torture the data into saying.

Brad DeLong makes the case that virtually all economic hypotheses are wrong, and the results from other meta-analyses are also worrying."

El economista James Galbraith (hijo de John Kenneth) es aún mas duro en su crítica:

"So what is modern economics about? It seems to be, mainly, about itself: The AEA meets to celebrate the importance of its members, their presence in high public positions, their influence in foreign lands, and the winning of the Nobel Prize. Female and black members have won the right to organize sessions about gender and race--thus domesticating some of those who might otherwise complain. Radicals and Keynesians, on the other hand, appeared only on panels organized separately, by an alphabet soup of splinter associations. What was therefore most conspicuously missing from this meeting of America's premier social science organization, was any actual discussion of economic ideas.....Leading active members of today's economics profession, the generation presently in their 40s and 50s, have joined together into a kind of politburo for correct economic thinking. As a general rule--as one might expect from a gentleman's club--this has placed them on the wrong side of every important policy issue, and not just recently but for decades. They predict disaster where none occurs. They deny the possibility of events that then happen. They offer a "rape is like the weather" fatalism about an "inevitable" problem (pay inequality) that then starts to recede. They oppose the most basic, decent, and sensible reforms, while offering placebos instead. They are always surprised when something untoward (like a recession) actually occurs."

Sin embargo, me parece que la mejor crítica viene de Nassim Taleb:

"We are good at fitting explanations to the past, all the while living in the illusion of understanding the dynamics of history.

My claim is about the severe overestimation of knowledge in what I call the " ex post" historical disciplines, meaning almost all of social science (economics, sociology, political science) and the humanities, everything that depends on the non-experimental analysis of past data. I am convinced that these disciplines do not provide much understanding of the world or even their own subject matter; they mostly fit a nice sounding narrative that caters to our desire (even need) to have a story. The implications are quite against conventional wisdom. You do not gain much by reading the newspapers, history books, analyses and economic reports; all you get is misplaced confidence about what you know. The difference between a cab driver and a history professor is only cosmetic as the latter can express himself in a better way.

There is convincing but only partial empirical evidence of this effect. The evidence can only be seen in the disciplines that offer both quantitative data and quantitative predictions by the experts, such as economics. Economics and finance are an empiricist's dream as we have a goldmine of data for such testing. In addition there are plenty of "experts", many of whom make more than a million a year, who provide forecasts and publish them for the benefits of their clients. Just check their forecasts against what happens after. Their projections fare hardly better than random, meaning that their "stories" are convincing, beautiful to listen to, but do not seem to help you more than listening to, say, a Chicago cab driver. This extends to inflation, growth, interest rates, balance of payment, etc. (While someone may argue that their forecasts might impact these variables, the mechanism of "self-canceling prophecy" can be taken into account). Now consider that we depend on these people for governmental economic policy!......

If you look closely at the data to check the reasons of this inability to see things coming, you will find that these people tend to guess the regular events (though quite poorly); but they miss on the large deviations, these " unusual" events that carry large impacts. These outliers have a disproportionately large contribution to the total effect.
Now I am convinced, yet cannot prove it quantitatively, that such overestimation can be generalized to anything where people give you a narrative-style story from past information, without experimentation. The difference is that the economists got caught because we have data (and techniques to check the quality of their knowledge) and historians, news analysts, biographers, and "pundits" can hide a little longer."