ColloquiaDaniel Osherson's talk on Wed. April 24

[Margery Ishmael]

Wednesday, April 24
at 2:30 pm
in Ryerson 251

"Coherent probability from incoherent estimates of chance"

DANIEL OSHERSON, Department of Psychology at Rice University

ABSTRACT:
Human judgment is an essential source of Bayesian probabilities but is 
plagued by incoherence when complex or conditional events are involved. We 
consider a method for adjusting estimates of chance over boolean events so 
as to render them probabilistically coherent. The feasibility of
our method was tested by randomly generating sets of coherent and 
incoherent estimates of chance over 20 to 50 variables. Even with 50 
variables, good approximations were computed within a few hours. Empirical 
test was provided by asking people to estimate the chances of
events relating to the stock market. The estimates of each participant were 
incoherent but well approximated by the coherent distribution
constructed for him. In addition, the quadratic scores of the reconstructed 
estimates were reliably superior to the scores of the original estimates. 
In this sense, our correction method improves the objective accuracy of the 
judgments that it renders coherent. http://www.ruf.rice.edu/~osherson/

Host: Partha Niyogi

*The talk will be followed by refreshments in Ryerson 255*
Persons with disabilities who may need assistance should call 773.834.8977

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Margery Ishmael
Secretary to the Chairman, Department of Computer Science
The University of Chicago
tel. 773.834.8977  fax. 773.702.8487
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