Dienstag, 5. November 2013

Rationale Erwartungen

Nicht gut oder schlecht ... man muss nur wissen, was man damit macht.

Mark Thoma (der mit dem Blog Economist's View) hat anlässlich der diesjährigen Verleihung des Nobelpreises einen Beitrag über die Annahme rationaler Erwartungen in der VWL geschrieben.
"Rational expectations are important for two reasons. First, they serve as a “perfect case” benchmark. In order to understand departures from rationality such as those embraced by Shiller, we need to know how the economy will function if agents fully understand everything about the economy, and can process the information optimally.

Assuming rational expectations is like assuming a perfect vacuum in physics – it provides a baseline that can be augmented with real-world features. Second, there are cases – simple games and financial markets for example – where the assumption of rational expectations may be approximately satisfied. But it’s a mistake, I think, to assume that rational expectations apply in all other settings or to the economy as a whole.

Economists need to know a lot more about when rational expectations apply and when they do not, and we need to amend our models appropriately. Behavioral economics is pushing us in this direction and providing some of the answers, but we have a long way to go before we’ll understand where and when the assumption of rational expectations is warranted."
Mein Eindruck ist auch, dass die Annahme rationaler Erwartungen oft hilfreich (oder notwendig) ist, um bestimmte Sachverhalte zu analysieren, dass bei der Interpretation der Ergebnisse aber nicht stark genug abgewogen wird, wie plausibel die Annahme in einem bestimmten Fall ist.
Rational expectations are important for two reasons. First, they serve as a “perfect case” benchmark. In order to understand departures from rationality such as those embraced by Shiller, we need to know how the economy will function if agents fully understand everything about the economy, and can process the information optimally.
Assuming rational expectations is like assuming a perfect vacuum in physics – it provides a baseline that can be augmented with real-world features. Second, there are cases – simple games and financial markets for example – where the assumption of rational expectations may be approximately satisfied. But it’s a mistake, I think, to assume that rational expectations apply in all other settings or to the economy as a whole.
Economists need to know a lot more about when rational expectations apply and when they do not, and we need to amend our models appropriately. Behavioral economics is pushing us in this direction and providing some of the answers, but we have a long way to go before we’ll understand where and when the assumption of rational expectations is warranted.
- See more at: http://www.thefiscaltimes.com/Columns/2013/11/05/How-Economists-Can-Tame-Irrational-Exuberance#sthash.fPektbnR.dpuf
Rational expectations are important for two reasons. First, they serve as a “perfect case” benchmark. In order to understand departures from rationality such as those embraced by Shiller, we need to know how the economy will function if agents fully understand everything about the economy, and can process the information optimally.
Assuming rational expectations is like assuming a perfect vacuum in physics – it provides a baseline that can be augmented with real-world features. Second, there are cases – simple games and financial markets for example – where the assumption of rational expectations may be approximately satisfied. But it’s a mistake, I think, to assume that rational expectations apply in all other settings or to the economy as a whole.
Economists need to know a lot more about when rational expectations apply and when they do not, and we need to amend our models appropriately. Behavioral economics is pushing us in this direction and providing some of the answers, but we have a long way to go before we’ll understand where and when the assumption of rational expectations is warranted.
- See more at: http://www.thefiscaltimes.com/Columns/2013/11/05/How-Economists-Can-Tame-Irrational-Exuberance#sthash.fPektbnR.dpuf
Rational expectations are important for two reasons. First, they serve as a “perfect case” benchmark. In order to understand departures from rationality such as those embraced by Shiller, we need to know how the economy will function if agents fully understand everything about the economy, and can process the information optimally.
Assuming rational expectations is like assuming a perfect vacuum in physics – it provides a baseline that can be augmented with real-world features. Second, there are cases – simple games and financial markets for example – where the assumption of rational expectations may be approximately satisfied. But it’s a mistake, I think, to assume that rational expectations apply in all other settings or to the economy as a whole.
Economists need to know a lot more about when rational expectations apply and when they do not, and we need to amend our models appropriately. Behavioral economics is pushing us in this direction and providing some of the answers, but we have a long way to go before we’ll understand where and when the assumption of rational expectations is warranted.
- See more at: http://www.thefiscaltimes.com/Columns/2013/11/05/How-Economists-Can-Tame-Irrational-Exuberance#sthash.fPektbnR.dpuf

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