Lars P. Syll

Det är i dag viktigare än någonsin att ompröva de senaste decenniernas finanspolitiska passivitet och för våra samhällen ofta kostsamma återhållsamhet. Förvisso har The New York Times rätt när de proklamerade häromdagen att det tycks som om ”alla blir socialister i en pandemi”. När krisen väl är framme tenderar de flesta, från höger till vänster, att förlita sig på statliga och offentliga lösningar. Den privata marknaden är inget att hålla i handen under en kris. Även...

Die nächste Krise — sind wir bereit?  [embedded content]

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Why are election polls often inaccurate? Why is racism wrong? Why are your assumptions often mistaken? The answers to all these questions and to many others have a lot to do with the non-ergodicity of human ensembles. Many scientists agree that ergodicity is one of the most important concepts in statistics. So, what is it? Suppose you are concerned with determining what the most visited parks in a city are. One idea is to take a momentary snapshot: to see how many people are...

Machine learning — puzzling ‘big data’ nonsense If we wanted highly probable claims, scientists would stick to​​ low-level observables and not seek generalizations, much less theories with high explanatory content. In this day​ of fascination with Big data’s ability to predict​ what book I’ll buy next, a healthy Popperian reminder is due: humans also want to understand and to explain. We want bold ‘improbable’ theories. I’m a little puzzled when I hear...

That’s the right spirit for coping with the coronavirus lockdown!  [embedded content]

Statistical models for causation — a critical review Causal inferences can be drawn from nonexperimental data. However, no mechanical rules can be laid down for the activity. Since Hume, that is almost a truism. Instead, causal inference seems to require an enormous investment of skill, intelligence, and hard work. Many convergent lines of evidence must be developed. Natural variation needs to be identified and exploited. Data must be collected. Confounders...

Requiem for my friend  [embedded content] In loving memory of Bengt Nilsson — a friend non plus ultra.

Are we all behavioural economists now? Postwar neoclassical economics was a reaction against a set of approaches based on the principles of hedonic psychology … Various developments in positive and normative economics had reassured them that references to unobservable entities were not only illegitimate but also dispensable. Thus, the concept of preference came to be the primitive notion of economic theory, and references to psychological theory were to be...

Judea Pearl and interventionist causal models (wonkish) As X’s effect on some other variable in the system S depends on there being a possible intervention on X, and the possibility of an intervention in turn depends on the modularity of S, it is a necessary condition for something to be a cause that the system in which it is a cause is modular with respect to that factor. The requirement that all systems are modular with respect to their causes can, in a...