Excess demand functions with incomplete markets—a global result

The purpose of this paper is to give a global characterization of excess demand functions in a two-period exchange economy with incomplete real asset markets. We show that continuity, homogeneity and Walras’ law characterize the aggregate excess demand functions on any compact price set which maintains the dimension of the budget set.     

Decrease in American birth rates makes it imperative for the United States to implement state mandated fertility coverage

In recent years, the prevalence of infertility has increased due to delayed childbearing and an increase in the rate of male infertility. Given the high cost of fertility treatment, this option is not valid for families with a low income, and those who can afford it usually choose to have multiple embryo transfer, which has led to an increase in multiple birth rates and an increase in the cost of perinatal care. Due to the expected increase in infertility and decrease in the national live birth rate, the US should set a plan to fund infertility treatment and lead a policy for single embryo transfer. This will offset the decrease in the national birth rates and decrease expenditure on perinatal and neonatal complications resulting from multiple births.     

Marketing’s roles in innovation in business-to-business firms: Status, issues, and research agenda

A project funded by the Institute for the Study of Business Markets to develop an understanding of the current state of business-to-business marketing and a research agenda for the field identified a lack of understanding of how the marketing function can or should best contribute to firms’ innovation efforts as the top priority. A workshop of senior academics and research-oriented practitioners explored this topic further, identifying four specific themes: (1) improving customer needs understanding and customer involvement in developing new products, (2) innovating beyond the lab, (3) disseminating and implementing research findings in firms, and (4) marketing’s overall role in innovation. This article defines these themes, sketches the current status of knowledge about each theme, frames practitioners’ issues with them, and proposes research agendas for each theme to move the field forward. The goal is to encourage rigorously executed academic research that can also help firms innovate more successfully.     

Note on the non-existence of sunspot equilibrium

In this note, we emphasize the role of consumers’ risk aversion in the non-existence of sunspot equilibria in incomplete market economies. We prove that there are no sunspot equilibria if the fundamentals of the underlying economy admit a unique equilibrium for any distribution of endowments. This substantiates Mas-Colell’s (Economic analysis of markets and games: essays in honor of Frank Hahn. MIT, Cambridge, 1992) conjecture. We also prove that, in a two-consumer economy, no sunspot equilibrium exists under the more relaxed condition that the underlying economy admits a unique equilibrium for the initial endowment. This is a generalization of Corollaries 1 and 2 of Hens and Pilgrim (Econ Theory 24:583–602, 2004).      

The effect of benefits level on take-up rates: evidence from a natural experiment

This paper exploits a quasi-natural experiment to study the effect of social benefits level on take-up rates. We find that households who are eligible for double benefits (twins) have much higher take-up rate—up to double—as compared to a control group of households. Our estimated effect of benefits level is much higher relative to the standard cross section estimates. This finding is less exposed to a selection bias that might plague much of the previous research on the link between benefits level and take-up. It provides strong empirical support for the level of benefits as a key factor in determining take-up rates.     

The Predictive Power of Internet-Based Product Concept Testing Using Visual Depiction and Animation

One critical step in new product development is selecting from among multiple possible product concepts the one that the firm will carry forward into the marketplace. There is a need for low‐cost, parallel testing of the appeal of new product concepts, the results of which closely mirror ultimate market performance. In this article, the authors first describe an Internet‐based product concept testing method they developed that incorporates virtual prototypes of new product concepts, substituting them for physical prototypes. The method can be used with either static representations of the products or with dynamic representations that demonstrate how the product works through a simulated video clip of its operation. The objective of this method is to allow design teams to select the best of several new concepts within a product category with which to proceed, without having to develop physical prototypes. The authors then provide a rigorous test of both virtual prototype methods against tests using both physical prototypes and attribute‐only (i.e., no visuals), full‐profile conjoint analysis. Nine concepts compete against two actual products in the tests. Market shares from the test using the physical prototypes are defined as the “actual” market shares. Predicted market shares for the attribute‐only, full‐profile conjoint analysis and each of the two virtual prototype methods are compared to those obtained for the physical prototypes. Both static and animated virtual prototype tests produced market shares that closely mirrored those obtained with the physical products, outperforming the set of predictions across the full range of products produced in the attribute‐only conjoint analysis. Interestingly, the attribute‐only conjoint analysis identified the top three products, in correct order. It was unable to differentiate performance below these top three products. Furthermore, it predicted market shares for the top three products to be well below those achieved using physical prototypes. As virtual prototypes cost considerably less to build and test than their physical counterparts, design teams using Internet‐based product concept research may be able to afford to explore a much larger number of concepts. Virtual prototypes and the testing methods associated with them may help reduce the uncertainty and cost of new product introductions by allowing more ideas to be concept tested in parallel with target consumers.     

The virtual customer

Communication and information technologies are adding new capabilities for rapid and inexpensive customer input to all stages of the product development (PD) process. In this article we review six web‐based methods of customer input as examples of the improved Internet capabilities of communication, conceptualization, and computation. For each method we give examples of user‐interfaces, initial applications, and validity tests. We critique the applicability of the methods for use in the various stages of PD and discuss how they complement existing methods. For example, during the fuzzy front end of PD the information pump enables customers to interact with each other in a web‐based game that provides incentives for truth‐telling and thinking hard, thus providing new ways for customers to verbalize the product features that are important to them. Fast polyhedral adaptive conjoint estimation enables PD teams to screen larger numbers of product features inexpensively to identify and measure the importance of the most promising features for further development. Meanwhile, interactive web‐based conjoint analysis interfaces are moving this proven set of methods to the web while exploiting new capabilities to present products, features, product use, and marketing elements in streaming multimedia representations. User design exploits the interactivity of the web to enable users to design their own virtual products thus enabling the PD team to understand complex feature interactions and enabling customers to learn their own preferences for new products. These methods can be valuable for identifying opportunities, improving the design and engineering of products, and testing ideas and concepts much earlier in the process when less time and money is at risk. As products move toward pretesting and testing, virtual concept testing on the web enables PD teams to test concepts without actually building the product. Further, by combining virtual concepts and the ability of customers to interact with one another in a stock‐market‐like game, securities trading of concepts provides a novel way to identify winning concepts. Prototypes of all six methods are available and have been tested with real products and real customers. These tests demonstrate reliability for web‐based conjoint analysis, polyhedral methods, virtual concept testing, and stock‐market‐like trading; external validity for web‐based conjoint analysis and polyhedral methods; and consistency for web‐based conjoint analysis versus user design. We report on these tests, commercial applications, and other evaluations. © 2002 Elsevier Science Inc. All rights reserved.