Explosive Extremal Convexity of the Value Function in Learning Models

(Axel Anderson and Lones Smith)

This paper studies learning in binary state models. For twice smooth policies, we precisely characterize the behavior of the implied value function in a general class of experimentation problems near the extreme beliefs 0 and 1. In particular, we show that under general assumptions v''(x) exists near x=0 and x=1, and satisfies v''(x)~ c0 x-a near x=0 and v''(x)~ c1(1-x)-b near x=1. Notably, we provide an exact formula for the exponents 0<a,b<1, and bound the coefficients c0,c1>0. An example illustrates how this result can be useful in applications.
 

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