A continuous location problem with different norms

This paper considers a set of problems of fixing the number and location of facilities to cover a given set of demand points, such that each demand point is served within a range of known distance standards, where each facility can be located on the entire plane and the distance can be either measured in rectilinear, Euclidean or Tchebycheff units. It is shown that an optimum solution can always be found on a small finite set of points. Thus the optimum itself can be found by either complete enumeration of these points or by zero one integer linear programming techniques. Furthermore, it is shown that the least and the largest number of facilities are required for the rectilinear and the Tchebycheff cases respectively.     

When Does a Platform Create Value by Limiting Choice?

We present a theory for why it might be rational for a platform to limit the number of applications available on it. Our model is based on the observation that even if users prefer application variety, applications often also exhibit direct network effects. When there are direct network effects, users prefer to consume the same applications to benefit from consumption complementarities. We show that the combination of preference for variety and consumption complementarities gives rise to (i) a commons problem (to better satisfy their individual preference for variety, users have an incentive to consume more applications than the number that maximizes joint utility); (ii) an equilibrium selection problem (consumption complementarities often lead to multiple equilibria, which result in different utility levels for the users); and (iii) a coordination problem (lacking perfect foresight, it is unlikely that users will end up buying the same set of applications). The analysis shows that the platform can resolve these problems and create value by limiting the number of applications available. By limiting choice, the platform may create new equilibria (including the allocation that maximizes users' utility); eliminate equilibria that give lower utility to the users; and reduce the severity of the coordination problem faced by users.     

Network structure,games, and agent dynamics

Consider a group of agents embedded in a network, repeatedly playing a game with their neighbors. Each agent acts locally but through the links of the network local decisions percolate to the entire population. Past research shows that such a system converges either to an absorbing state (a fixed distribution of actions that once attained does not change) or to an absorbing set (a set of action distributions that may cycle in finite populations or behave chaotically in unbounded populations). In many network games, however, it is uncertain which situation emerges. In this paper I identify two fundamental network characteristics, boundary consistency and neighborhood overlap, that determine the outcome of all symmetric, binary-choice, network games. In quasi-consistent networks these games converge to an absorbing state regardless of the initial distribution of actions, and the degree to which neighborhoods overlap impacts the number and composition of those absorbing states.     

Transversals, systems of distinct representatives, mechanism design, and matching

A transversal generated by a system of distinct representatives (SDR) for a collection of sets consists of an element from each set (its representative) such that the representative uniquely identifies the set it belongs to. Theorem 1 gives a necessary and sufficient condition that an arbitrary collection, finite or infinite, of sets, finite or infinite, have an SDR. The proof is direct, short. A Corollary to Theorem 1 shows explicitly the application to matching problems. In the context of designing decentralized economic mechanisms, it turned out to be important to know when one can construct an SDR for a collection of sets that cover the parameter space characterizing a finite number of economic agents. The condition of Theorem 1 is readily verifiable in that economic context. Theorems 2–5 give different characterizations of situations in which the collection of sets is a partition. This is of interest because partitions have special properties of informational efficiency.     

Autonomy in the industrial R&D lab

This article distinguishes between “strategic autonomy” (the freedom to set one's own research agenda) and “operational autonomy” (the freedom, once a problem has been set, to attack it by means determined by oneself, within given resource constraints). The article argues, and presents some preliminary corroborating data, that technical careers in the R&D lab should start lower on strategic than on operational autonomy, that operational autonomy should show initial fairly rapid increase, which should be followed by increases in strategic autonomy, and that thereafter a number of different career paths should be available for technical employees. Most labs, however, seem to espouse a philosophy of strategic autonomy combined with operational controls, which creates dilemmas and contradictions in the technical career, particularly at its start. It is proposed that these two aspects of autonomy can usefully be thought of as a two-dimensional grid. Different positions on this grid seem to fit with different orientations and different tasks, and require different strategies for career management. The article ends with a discussion of these management implications.     

The Market Concept: A Characterization from Institutional and Post‐Keynesian Economics

The neoclassical concept of the market is built on a number of assumptions that lead one to view it as a type of ether, devoid of any institutional content. In opposition to this point of view, this article proposes an alternative characterization of markets based on the fundamental principles of institutional and post‐Keynesian economics. After reviewing the main features that characterize the behavior of economic agents, we analyze the set of interrelations between these agents within markets and the role of institutions in the regulation of these interrelations. Finally, we discuss some of the consequences generated by the institutional dimensions of markets with regard to their origins and evolution, the justification for their existence, or the evaluation of their results.     

Charity Art Auctions

Using a unique panel data set of art auctions on eBay, we conduct an empirical analysis of the impact of charity status on the outcome of an auction and find it to be substantial. Charity status increases the probability of sale by 46%, the observed number of bidders by 111% and the sale price by 45%. In addition, charity status substantially lowers the auction's opening price. Interestingly, the effect of charity status declines over time indicating that charity auctions may be susceptible to donor fatigue.     

Utility functions on ordered convex sets

The work of Cantor in set theory near the end of the last century showed that a linearly ordered set need not be order isomorphic to a subset of the real numbers. To obtain order isomorphism, it is necessary and sufficient that some countable subset of the linearly ordered set be order- dense in the entire set. The present paper proves a negative result that is much stronger than Cantor's. It shows that a weakly ordered convex set whose order relation is ‘continuous’ and ‘totally convex’ need not be order homomorphic to a subset of the reals. To obtain order homomorphism, it is necessary and sufficient that the weakly ordered set be countably bounded, i.e., have countable coinitial and cofinal subsets. Countable boundedness is a significantly weaker condition than countable order-denseness. Connections between these results and economic utility theory are discussed.     

A generalized focused information criterion for GMM

This paper proposes a criterion for simultaneous generalized method of moments model and moment selection: the generalized focused information criterion (GFIC). Rather than attempting to identify the “true” specification, the GFIC chooses from a set of potentially misspecified moment conditions and parameter restrictions to minimize the mean squared error (MSE) of a user‐specified target parameter. The intent of the GFIC is to formalize a situation common in applied practice. An applied researcher begins with a set of fairly weak “baseline” assumptions, assumed to be correct, and must decide whether to impose any of a number of stronger, more controversial “suspect” assumptions that yield parameter restrictions, additional moment conditions, or both. Provided that the baseline assumptions identify the model, we show how to construct an asymptotically unbiased estimator of the asymptotic MSE to select over these suspect assumptions: the GFIC. We go on to provide results for postselection inference and model averaging that can be applied both to the GFIC and various alternative selection criteria. To illustrate how our criterion can be used in practice, we specialize the GFIC to the problem of selecting over exogeneity assumptions and lag lengths in a dynamic panel model, and show that it performs well in simulations. We conclude by applying the GFIC to a dynamic panel data model for the price elasticity of cigarette demand.     

Impossibilities for strategy-proof committee selection mechanisms with vetoers

When a group of voters selects a committee out of a set of candidates, it is common and often desirable to endow these voters with some veto power. I present impossibility results showing that even limited veto power makes many mechanisms of interest manipulable. This applies in particular (i) to mechanisms the range of which contains a degenerate lottery in which a committee is chosen for sure and (ii) to mechanisms that are constructed from extensive game forms with a finite number of strategies. These impossibilities hold on a large set of domains including the domain of additive preferences, and even when probabilistic mechanisms are allowed and voters can report cardinal preferences.     

Effective Repair in Survey Interviews

In standardized survey interviews with closed-ended questions it quite often occurs that respondents do something else than mentioning their choice from the set of response categories presented together with the question. In these cases their initial response is inadequate and interviewers have to initiate repair activities. By analyzing 804 question–answer sequences, stemming from parts of a survey with elderly people (N=201), we found that 322 (41%) of the initial responses were inadequate. In 74% of these 332 sequences the interviewers made an attempt at repair. Of all repair attempts, 75% were performed correctly, that is, in a nondirective way. Most of the repair attempts (86%) result in an adequate final response of the respondent. The result of the repair activities by the interviewers is that the number of sequences with an adequate response increased from 472 to 688, thus an increase of about 45%. There does not exist ‘one best way’ of repairing. The most important thing is that some repair initiative has to be taken by the interviewer and that the repair is done in a nondirective way.     

The renewed ‘American Challenge’: a review of employment practice in US multinationals

Despite the extensive literature concerned with IR practice in American multinational companies (MNCs), there are serious gaps in our understanding of how this group of firms manages their international workforces. In this paper, we set out a framework of ‘four key influences’ on the way MNCs approach the management of labour and go on to use this framework to assess existing literature concerned with US MNCs. While this review reveals a number of general tendencies—for example, American MNCs tend to be highly centralised in the decision making on IR matters—it also reveals a number of gaps and weaknesses. In particular, we argue that previous research has failed to develop a convincing understanding of how the ‘embeddedness’ of US MNCs in their country of origin informs the behaviour of these firms as employers outside the USA. The paper ends by outlining a programme of research into US MNCs.     

公路桥梁施工技术质量的探讨

随着经济的快速发展,在公路工程施工中,需要架设数座桥梁,公路桥梁是现代社会建设的重要设施。在公路桥梁项目的施工中,如何运用科学的施工方法,合理的施工,确保公路桥梁的施工质量,是建设单位应该重点探讨的问题,同时保证工程质量和降低施工人员事故率具有积极意义。     

De invloed van de keuze der gewichten op de hoogte van een gewogen indexcijfer

The influence of the choice of the weights on the value of an indexnumber.
Price and quantity indexnumbers are weighted averages of groups of price and quantity ratios and they are convenient instruments to indicate the general tendency of such groups, especially if the number of basic ratios is considerable. The frequent use of indexnumbers is due to the fact that they can often be applied to problems for which, strictly speaking, an indexnumber had to be used derived from the same group of ratios but based on a different set of weights.
Two typical examples of such problems are given.
The use of a set of weights differing from the appropriate one is only justified, however, when the indexnumber is rather insensitive to changes in the set of weights. A simple formula is derived showing that the relative change of an index-number due to a change in the set of weights is equal to the product of the (weighted) coefficient of variation of the basic ratios, the (weighted) standard deviation of the relative changes of the weights and the (weighted) coefficient of correlation of the ratios and of the relative changes. The system of weights used in the calculation of these three factors is the same and is equal to the set of true weights belonging to the problem under consideration.
The practical use of the formula is demonstrated at the problem of index-numbers of costs frequently encountered in the practice of cost accounting.     

Managing Employee Social Networking: Evolving Views from the National Labor Relations Board

With the development of social networking internet sites such as Myspace, Facebook, and Twitter, a new set of concerns has arisen for employers. A growing number of employers has asserted a right to regulate employee use of the internet and social networking sites despite the fact that such policies may be seen as an intrusion on workers’ privacy interests. This paper explores the conflict between the employees’ interest in internet use and employer efforts to regulate and control these activities. A number of National Labor Relations Board cases and supporting reports, as well as, arbitration decisions are examined in order to explore the critical issues that have emerged regarding employee use of social networking. Based on an analysis of the cases and literature, guidelines are provided for effective employer social networking policies. A high quality policy and an understanding of the changing standards are critical for successful management of employee social networking.     

Geodesics on the equilibrium manifold

We show the existence of a Riemannian metric on the equilibrium manifold such that a minimal geodesic connecting two (sufficiently close) regular equilibria intersects the set of critical equilibria in a finite number of points. This metric represents a solution to the following problem: given two (sufficiently close) regular equilibria, find the shortest path connecting them which encounters the set of critical equilibria in a finite number of points. Furthermore, this metric can be constructed in such a way to agree, outside an arbitrary small neighborhood of the set of critical equilibria, to any given metric with economic meaning.     

GMM redundancy results for general missing data problems

We consider questions of efficiency and redundancy in the GMM estimation problem in which we have two sets of moment conditions, where two sets of parameters enter into one set of moment conditions, while only one set of parameters enters into the other. We then apply these results to a selectivity problem in which the first set of moment conditions is for the model of interest, and the second set of moment conditions is for the selection process. We use these results to explain the counterintuitive result in the literature that, under an ignorability assumption that justifies GMM with weighted moment conditions, weighting using estimated probabilities of selection is better than weighting using the true probabilities. We also consider estimation under an exogeneity of selection assumption such that both the unweighted and the weighted moment conditions are valid, and we show that when weighting is not needed for consistency, it is also not useful for efficiency.     

Sequential estimate for linear regression models with uncertain number of effective variables

As a result of novel data collection technologies, it is now common to encounter data in which the number of explanatory variables collected is large, while the number of variables that actually contribute to the model remains small. Thus, a method that can identify those variables with impact on the model without inferring other noneffective ones will make analysis much more efficient. Many methods are proposed to resolve the model selection problems under such circumstances, however, it is still unknown how large a sample size is sufficient to identify those “effective” variables. In this paper, we apply sequential sampling method so that the effective variables can be identified efficiently, and the sampling is stopped as soon as the “effective” variables are identified and their corresponding regression coefficients are estimated with satisfactory accuracy, which is new to sequential estimation. Both fixed and adaptive designs are considered. The asymptotic properties of estimates of the number of effective variables and their coefficients are established, and the proposed sequential estimation procedure is shown to be asymptotically optimal. Simulation studies are conducted to illustrate the performance of the proposed estimation method, and a diabetes data set is used as an example.     

The future's poor: Projecting the population eligible for federal housing assistance

Microanalytic simulation techniques are used to show that, under a reasonable set of assumptions, the real income of elderly households can be projected to grow at a rate higher than that of other population groups over the next several decades. Simulation modeling also shows that current low marriage and fertility rates and high divorce rates, if continued, will lead to a future population that is proportionately more elderly and of smaller average family size. A number of federal, state, and local assistance programs restrict eligibility to low-income households. In an application to the major federal housing assistance program, it is shown that future growth in the number of elderly households may well be offset by their relatively high income growth, leaving the proportion elderly among those eligible for assistance essentially unchanged over the next 40 years. The findings imply that future changes in the demographic composition of the U.S. population may not be reflected in the composition of the low-income population. This possibility should be considered in planning assistance programs targeted on the poor.