Lars P. Syll

What went wrong with economics? Internal coherence is one way of adjudicating among theories, but so is correspondence to everyday life. Too much realism may kill analysis, but too little realism is unscientific. If theoretical coherence alone were all that mattered, then the only constraint on theoretical exercises would be the human imagination. Interesting puzzles would replace pragmatic solutions to problems encountered in the world — arguably, an accurate characterization of most...

No realism please. We’re Chicago economists! Samuelson’s reconciliation of the micro-economic ideal type with involuntary unemployment was repudiated, along with Keynesian prescriptions, in favor of a view that there could be no involuntary unemployment , hence that government action was unnecessary. The result was a doctrinaire derivation of the laissez-faire conclusions that had been overturned by the formalist revolution; economics was now cleansed of Keynesian impurities that had been...

Efficient Market Hypothesis — an intellectually lazy ideology Both Brad DeLong and Noah Smith have posts up on their blogs commenting on the status of the Efficient Market Hypothesis. As so often the really interesting questions however drown in the usual mumbo jumbo “the model is the message” pseudo science of four-factor models with two mispricing factors being better-performing than three-factor models … Diane Coyle has a much more accurate view of what it’s all about: I would defend...

Economist Brian Arthur has made important contributions to our understanding of inductive versus deductive approaches to problem solving. Arthur notes that you can solve only the easiest problems deductively … But humans are superb at recognizing and matching patterns. We’re inductive machines. Arthur offers a model of inductive reasoning, effectively picking up where Lord Keynes left off. The model is based on the El Farol bar in Santa Fe, New Mexico … Attending the El Farol when it...

Thank God Eric Schüldt is back! I dessa tider — när ljudrummet dränks i den kommersiella radions tyckmyckentrutade ordbajseri och fullständigt intetsägande melodifestivalskval — har man ju nästan gett upp. Men det finns ljus i mörkret! I radions P2 går varje lördagmorgon ett vederkvickelsens och den seriösa musikens Lördagsmorgon i P2. Så passa på och börja dagen med en musikalisk örontvätt och rensa hörselgångarna från kvarvarande musikslagg. Här kan man till exempel lyssna på musik av...

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Applied econometrics — a messy business The applied econometrician is like a farmer who notices that the yield is somewhat higher under the trees where birds roost, and he uses this for evidence that bird droppings increase the yield. However, when he presents his findings … another farmer … objects that he used the same data but came up with the conclusion that moderate amounts of shade increase the yields … A bright chap … then observes that these two hypotheses are indistinguishable,...

Variable selection — not about having a ‘good fit’ Which independent variables should be included in the equation? The goal is a “good fit” … How can a good fit be recognized? A popular measure for the satisfactoriness of a regression is the coefficient of determination, R2. If this number is large, it is said, the regression gives a good fit … Nothing about R2 supports these claims. This statistic is best regarded as characterizing the geometric shape of the regression points and not much...

Should we ‘control for’ everything when running regressions? No way! When I present this argument … one or more scholars say, “But shouldn’t I control for everything I can in my regressions? If not, aren’t my coefficients biased due to excluded variables?” This argument is not as persuasive as it may seem initially. First of all, if what you are doing is misspecified already, then adding or excluding other variables has no tendency to make things consistently better or worse … The excluded...

To a mainstream economist, theory means model, and model means ideas expressed in mathematical form. In learning how to “think like an economist,” students learn certain critical concepts and models, ideas which typically are taught initially through simple mathematical analyses. These models, students learn, are theory. In more advanced courses, economic theories are presented in more mathematically elaborate models. Mainstream economists believe proper models – good models – take a...