Finite project life and uncertainty effects on investment

This paper revisits the important result of the real options approach to investment under uncertainty, which states that increased uncertainty raises the value of waiting and thus decelerates investment. Typically in this literature projects are assumed to be perpetual. However, in today's economy firms face a fast-changing technology environment, implying that investment projects are usually considered to have a finite life. The present paper studies investment projects with finite project life, and we find that, in contrast with the existing theory, investments may be accelerated by increased uncertainty. It is shown that this particularly happens at low levels of uncertainty and when project life is short.     

一个差分方程的动力行为

研究了一个四阶有理差分方程,证明了该方程的正平衡点是全局渐近稳定的.     

Optimal patent length and height

Patent breadth and length have been discussed extensively in innovation literature. In this article, I analyze the optimal degree of novelty of patent protection and its tradeoff with patent length. In the context of subsequent innovations each innovation builds on the previous one. The degree of novelty necessary for a non-infringing patent is crucial for the firms’ incentive to innovate. One of the findings is that a monopolist’s optimal degree of novelty is lesser than would be socially desirable. Furthermore, there exists a finite optimal patent length. Competitors introducing an improved technology cause uncertainty which may be compensated by extending patent length.

在计算机中解线性方程组的一种算法

本文直接根据行列式的定义，用QBASIC语言给出了计算行列式的算法。在运算过程中，只使用了乘法及加法运算，避免了因除法运算带来的计算误差，特别是行列式中的元素为整数并且计算结果是8位以下的整数时则完全没有误差，再使用克莱姆法则能求出线性方程组非常精确的解。     

The Effect of Length of Stay on Travelers' Perceived Satisfaction with Service Quality

SUMMARY

Consumer satisfaction related to service quality during the vacation experience is of paramount importance to the travel and tourism industry. This study tests empirically the effects the number of nights spent on a vacation have on the levels of satisfaction recent travelers report for three service aspects of the travel destination: perceived satisfaction with tourism service providers; perceived “freedom from defects” of tourism services; and perceived reasonableness of the cost of tourism services. Differentiation in satisfaction scores between “short-term visitors” (i.e., those who stayed from one to six nights) and “long-term visitors” (i.e., those who stayed seven or more nights) were examined. Significant differences between the two groups of visitors were present for (1) perceived satisfaction with industry professionals delivering the service experience at the travel destination, (2) perceived satisfaction with “freedom from defects” of the actual services at the destination, and (3) perceived reasonableness of the cost of services at the travel destination. Suggestions for how tourism industry professionals can make use of this information are presented.     

A better copyright system? comparing welfare of indefinitely renewable copyright versus fixed-length copyright

This study models and simulates fixed-length copyright (FLC) and indefinitely renewable copyright (IRC) and compares their social welfare. Evidence is found suggesting that IRC has lower maximal social welfare than FLC does. This difference can be explained by the way copyright duration is determined. Copyright duration represents the balance between encouraging creation and reducing restrictions on the consumption of information products. Under FLC, copyright duration is chosen directly by legislation; under IRC, it is induced indirectly through a copyright fee. However, the imposition of a copyright fee distorts the behavior of creators and thus decreases social welfare.     

板坯二次火切机控制系统应用

介绍了安钢第二炼轧厂板坯离线二次切割电气控制系统的组成及在生产中的应用情况。应用实践表明,二次切割系统的投产为安钢通过产品结构调整增效起到了积极作用。     

Regression Sampling in Statistical Auditing: A Practical Survey and Evaluation

Several confidence intervals for the regression estimator are surveyed. A Monte Carlo experiment, based on the NETER and LOEBBECKE (1975) populations, gives estimated coverages and lengths of the different confidence intervals. One interval is exact under the assumption of multivariate normal distributions; it gives longer intervals (hence better coverages) than the interval based on a popular variance estimator. An interval due to ROBERTS (1970) is much too long. Jackknifing gives robust intervals. Rules of thumb for practitioners are given.     

Asymptotic confidence intervals for the length of the shortt under random censoring

A short t of a one dimensional probability distribution is defined to be an interval which has at least probability t and minimal length. The length of a show and its obvious estimator are significant measures of scale of a distribution and the corresponding random sample, respectively. In this note a non-parametric asymptotic confidence interval for the length of the (uniqueness is assumed) short t is established in the random censorship from the right model. The estimator of the length of the short t is based on the product-limit (PL) estimator of the unknown distribution function. The proof of the result mainly follows from an appropriate combination of the Glivenko-Cantelli theorem and the functional central limit theorem for the PL estimator.     

Variables control chart limits and tests for special causes

Control charts are used to detect problems in control such as outliers, shifts in levels or excess variability in subgroup means that may have a special cause. This paper addresses itself to deriving control chart limits based on past data and based on initial samples in a current control situation. We present a general setting for control charts. Furthermore, an overview is given of tests for special causes. The tests are standardized so that the asymptotic type I error does not exceed a fixed level. The distributions of the run lengths of the tests and combinations of tests are also evaluated. We propose to use a low percen-tile of the run length distribution, instead of the average run length, to study the performance of the tests. These indicate that, in particular when tests are combined, the run length percentiles may be too small for practical purposes. It is shown that (nearly) exact control chart limits for observations from a normal distribution exist. The traditional limits differ considerably from the proposed ones and correspond to even smaller run length percentiles.