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STICERD Economic Theory Seminars

An Axiomatic Approach to the Law of Small Numbers

Jawwad Noor (Boston University), joint with Fernando Payro

Thursday 09 March 2023 15:30 - 17:00

32L 3.05, 3rd Floor Conference Room, LSE, 32 Lincoln's Inn Fields, London WC2A 3PH

Many of our seminars and public events this year will continue as in person or as hybrid (online and in person) events. Please check our website listings and Twitter feed @STICERD_LSE for updates.

Unless otherwise specified, in-person seminars are open to the public.

Those unable to join the seminars in-person are welcome to participate via zoom if the event is hybrid.

About this event

With beliefs over the outcomes of coin-tosses as our primitive, we formalize the Law of Small Numbers (Tversky and Kahneman (1974)) by an axiom that expresses a belief that the sample mean of any sequence will tend towards the coin’s perceived bias along the entire path. The agent is represented by a belief that the bias of the coin is path-dependent and self-correcting. The model is consistent with the evidence used to support the Law of Small Numbers, such as the Gambler’s Fallacy. In the setting of Bayesian inference, we show how learning is affected by the interplay between two potentially opposing forces: a belief in the absence of streaks and a belief that the sample mean will tend to the true bias. We show that, unlike other learning results in the literature (Rabin (2002), Epstein, Noor and Sandroni (2010)), the latter force ensures that the agent at least admits the true parameter as possible in the limit, if not learn with certainty that it is true. In an evolutionary setting, we show that agents who believe in the Law of Small Numbers are never pushed out of the evolutionary race by “standard" agents who correctly understand randomness.

Economic Theory Seminars are held on Thursdays in term time at 15:30-17:00, both ONLINE and IN PERSON in 32L 3.05.

Seminar organisers: Dr Andrew Ellis and Dr Christopher Sandmann.

For further information please contact Marta Wasik by email:

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This event will take place in 32L 3.05, 3rd Floor Conference Room, LSE, 32 Lincoln's Inn Fields, London WC2A 3PH.

The building is labelled 32L on the map. Enter the building via Lincoln's Inn Fields.

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