Economics Insights @ CBS

This study investigates the determinants of the expected stock-price volatility assumption that firms use in estimating ESO values and thus option expense. We find that, consistent with the guidance of FAS 123, firms use both historical and implied volatility in deriving the expected volatility parameter. We also find, however, that the importance of each of the two variables in explaining disclosed volatility relates inversely to their values, which results in a reduction in expected volatility and thus option value.

We consider importance sampling simulation for estimating rare event probabilities in the presence of heavy-tailed distributions that have polynomial-like tails. In particular, we prove the following negative result: there does not exist an asymptotically optimal state-independent change-of-measure for estimating the probability that a random walk (respectively, queue length for a single server queue) exceeds a "high" threshold before going below zero (respectively, becoming empty).

Public/private partnerships have become a favored strategy for implementing complex urban developments in the United States and Western Europe, but the large volume of literature on the topic falls short of providing city planners, development experts, and policy analysts the knowledge needed for either teaching or practice. In the late 1970s, the blurring of lines between public and private action spurred significant intellectual debate in the U.S.