The directional distance function model is a generalization of the radial model in data envelopment analysis (DEA). The directional distance function model is appropriate for dealing with cases where undesirable outputs exist. However, it is not a units-invariant measure of efficiency, which...

Influence maximization problem is about finding a small set of nodes from the social network as seed set so as to maximize the range of information diffusion. In this paper, the theory of coritivity and method of finding core nodes in networks are introduced to deal with this problem. From the...

Compared to mutual funds, hedge funds prefer smaller, opaque value securities, and have higher turnover and more active share bets. Decomposing returns into three components, we find that hedge funds are better than mutual funds at stock picking by only 1.32% per year on a value-weighted basis,...

In this paper we consider the problem of testing the hypothesis about the sub-mean vector. For this propose, the asymptotic expansion of the null distribution of Rao's U-statistic under a general condition is obtained up to order of n-1. The same problem in the k-sample case is also...

We consider a Stackelberg model under demand slope uncertainty in an environment where the follower owns information advantage. Specifically, we show that the second mover obtains higher expected profit than the first mover when the leader only knows the prior beliefs and the follower gains the...

Firms experiencing increases in import competition significantly reduce their leverage ratios by issuing equity and selling assets to repay debt. Using import tariffs and foreign exchange rates as instrumental variables for import penetration, I show that these results are not manifestations of...

In many polyandrous species, the last male to mate sires most of the offspring. This phenomenon has been explained as the result of male manipulation, postcopulatory female choice, or both. However, in most previous studies, direct evidence for these explanations is lacking. Here, we report our...