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1. Why Diagnostic Expectations Cannot Replace REH

Author:
Roman Frydman and Halina Frydman
Publication Date:
01-2022
Content Type:
Working Paper
Institution:
Institute for New Economic Thinking (INET)
Abstract:
Gennaioli and Shleifer (GS) have proposed diagnostic expectations (DE) as an empirically-based approach to specifying participants’ expectations, which, like REH, can be applied in every model. Beyond its supposedly general applicability, GS’s formalization of DE implies that participants systematically and predictably overreact to news. Here, we present a formal argument that Kahneman and Tversky’s compelling empirical findings, and those of other behavioral economists, do not provide a basis for a general approach to specifying participants’ “predictable errors.” We also show that the overreaction of participants’ expectations is not a regularity, but rather an artifact of GS’s particular specification of DE.
Topic:
Economics, Models, and Predictability
Political Geography:
Global Focus

2. Why Diagnostic Expectations Cannot Replace REH

Author:
Roman Frydman and Halina Frydman
Publication Date:
01-2022
Content Type:
Working Paper
Institution:
Institute for New Economic Thinking (INET)
Abstract:
Gennaioli and Shleifer (GS) have proposed diagnostic expectations (DE) as an empirically-based approach to specifying participants’ expectations, which, like REH, can be applied in every model. Beyond its supposedly general applicability, GS’s formalization of DE implies that participants systematically and predictably overreact to news. Here, we present a formal argument that Kahneman and Tversky’s compelling empirical findings, and those of other behavioral economists, do not provide a basis for a general approach to specifying participants’ “predictable errors.” We also show that the overreaction of participants’ expectations is not a regularity, but rather an artifact of GS’s particular specification of DE.
Topic:
Economics, Academia, and Models
Political Geography:
Global Focus

3. Asset Prices Under Knightian Uncertainty

Author:
Roman Frydman, Søren Johansen, Anders Rahbek, and Morten Tabor
Publication Date:
12-2021
Content Type:
Working Paper
Institution:
Institute for New Economic Thinking (INET)
Abstract:
We extend Lucas’s classic asset-price model by opening the stochastic process driving dividends to Knightian uncertainty arising from unforeseeable change. Implementing Muth’s hypothesis, we represent participants’ expectations as being consistent with our model’s predictions and formalize their ambiguity- averse decisions with maximization of intertemporal multiple-priors utility. We characterize the asset-price function with a stochastic Euler equation and derive a novel prediction that the relationship between prices and dividends undergoes unforeseeable change. Our approach accords participants’ expectations, driven by both fundamental and psychological factors, an autonomous role in driving the asset price over time, without presuming that participants are irrational.
Topic:
Economics, Models, and Price
Political Geography:
Global Focus