Confidence Intervals for the Area Under the Receiver Operating Characteristic Curve in the Presence of Ignorable Missing Data

Receiver operating characteristic curves are widely used as a measure of accuracy of diagnostic tests and can be summarised using the area under the receiver operating characteristic curve (AUC). Often, it is useful to construct a confidence interval for the AUC; however, because there are a number of different proposed methods to measure variance of the AUC, there are thus many different resulting methods for constructing these intervals. In this article, we compare different methods of constructing Wald‐type confidence interval in the presence of missing data where the missingness mechanism is ignorable. We find that constructing confidence intervals using multiple imputation based on logistic regression gives the most robust coverage probability and the choice of confidence interval method is less important. However, when missingness rate is less severe (e.g. less than 70%), we recommend using Newcombe's Wald method for constructing confidence intervals along with multiple imputation using predictive mean matching.     

The effect of human resource management practices on the perceptions of organizational and market performance of the firm

The purpose of our study is to extend the emerging empirical literature on the firm‐level impact of human resource management practices. Results based on a national sample of organizations from private and public sectors in Israel indicate that these practices have a significant impact on both the perceived organizational and market performance of the organization. The single independent variable found to be statistically significant in affecting perceived organizational performance was training practices. In the case of perceived market performance, we found that, in addition to training practices, employee selection practices also significantly affected the perceived market performance.¹ © 1999 John Wiley & Sons, Inc.     

Sabotaging in contests with monitoring efforts

This paper considers a 3‐stage contest with both sabotage and monitoring efforts that aim to reduce sabotage. In the first stage, the regulator sets his monitoring efforts for each contestant. In the second stage, each contestant determines his sabotaging efforts, based on the monitoring efforts that were imposed by the regulator. In the third stage, each contestant determines his productive efforts in the contest. The results supply a justification to exert monitoring efforts because these efforts may benefit both the contestants and the regulator (a win‐win situation). Furthermore, the paper defines the conditions where exerting monitoring efforts would be worthwhile.     

The role and contribution of networks in M&A of innovative ventures: can lessons learned from networks of Israeli start-ups be applied by China?

Networks’ impact on business outcome is documented in various theories. We examined the role of specific actors in the networks of successful Israeli technology ventures and identified the actor's contribution during early, advanced, and merger and acquisition (M&A) stages. A mixed qualitative–quantitative method was applied to collect insight and data from 185 founder-entrepreneurs who exited via M&A. A name generator-interpreter technique was used to obtain details on the role and contribution of 768 actors. Our findings pointed to the influential role of actors such as Venture Capitalists , angels, board members, and multinational firms, as well as the vital contribution of foreign actors, during M&A transactions. We further draw implications to illustrate that, if applied, lessons learned from sell-side acquired ventures can benefit Chinese companies in their quest to acquire innovation via M&A. We suggest that the understanding of networks practiced by acquired ventures can increase buyers’ accessibility and visibility to target opportunities and improve M&A outcomes.     

On the Market Failure in a Dixit-Stiglitz Setup with Two Trading Cities

This study discusses the reasons for market failure and its bias in an economy with two cities and two final goods: tradeable differentiated products and non‐tradeable housing. It is shown that inside the city, as in Dixit and Stiglitz (1977) , diversity (number of firms) is too small. With regard to the population partition between the cities, the paper distinguishes between a marginal and a global market bias against agglomeration or dispersion (in a second‐best context). The reasons for a marginal bias are twofold: a gap between marginal and average labor productivity and the (excessive) labor employed in housing production which vary between the large and the small cities. The source of the global bias is multiple stable equilibria. The marginal bias may be in an opposite direction to the global bias, such that more agglomeration may be marginally desirable, whereas full dispersion is (second‐best) optimal. Simulations demonstrate that the same market structure and potential source of market failure may imply bias in different directions, depending on the aggregate population size.     

A Little AI Goes a Long Way on Wall Street

This is a history and technical overview of one of the major AI successes in securities trading. It incorporates only as much AI as the financial user community could deal with, integrating tightly with their electronic environment. Computational resources are used to make a simple, highly application-specific user interface, a small firm has succeeded in developing a system used by many of the largest institutional investors and money managers in the USA. The system is directly linked to the NYSE and other electronic equity-execution systems. This is not a prototype or a proposal. This is real and in wide use today, often generating transaction volumes exceeding 5 million shares per day. Traders use a special-purpose rule-based language to describe a wide variety of market conditions. The system keeps up with high-speed incoming market data in real-time and tells the traders when, and how strongly, their specified conditions match the current state of the market. It can also formulate trading recommendations based on those conditions. Finally, and most importantly, it provides direct access to electronic execution channels for quick action on these recommendations. The combination of tight integration with both market data and electronic executions, an appropriate, accessible user interface, and a high level of support have contributed to a major AI success story. The transactions flowing through these systems produce more revenue on a good day than many other AI applications will generate over their entire operational lifetimes.     

麻省理工学院——如何建立反应灵敏的供应链？

自上世纪60年代以来，人们普遍接受的一个观点是，一家现代商业企业的必须有一个宽泛的战略愿景所引领。媒体企业应该成为传播自身原创内容的全球业务经营者，汽车企业应把自己看成整合交通系统的供应商，而电信公司当然应该提供无所不在的电子多媒体链接。     

When is the median voter paradigm a reasonable guide for policy choices in a representative democracy?

The median voter paradigm (MVP) has been widely used to study the interactions between economic and political behavior. While this approach is easy to work with, it abstracts from institutional detail. This paper explores whether the MVP leads on average to the same policies that would be chosen in a two-party representative democracy (RD). When it does not, the paper fully characterizes the size and magnitude of the average divergence (or bias) between policy choices in MVP and in RD in terms of the degree of polarization between the parties, their relative electoral prospects, and the distribution of electoral uncertainty. The results are then applied to the influential Meltzer and Richard (1981) theory of the size of government.