An algebraic theory of portfolio allocation

Summary. Using group and majorization theory, we explore what can be established about allocation of funds among assets when asymmetries in the returns vector are carefully controlled. The key insight is that preferences over allocations can be partially ordered via majorized convex hulls that have been generated by a permutation group. Group transitivity suffices to ensure complete portfolio diversification. Point-wise stabilizer subgroups admit sectoral separability in fund allocations. We also bound the admissible allocation vector by a set of linear constraints the coefficients of which are determined by group operations on location and scale asymmetries in the rate of returns vector. For a distribution that is symmetric under a reflection group, the linear constraints may be further strengthened whenever there exists an hyperplane that separates convex sets. Received: May 15, 2001; revised version: March 20, 2002 RID="*" ID="*" Journal paper No. J-19797 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa. Project No. 3463, and supported by Hatch Act and State of Iowa funds. Correspondence to: D. A. Hennessy     

The cost of diabetes and obesity in Australia

Aims: To assess and compare the direct healthcare and non-healthcare costs and government subsidies by body weight and diabetes status.

Methods: The Australian Diabetes, Obesity and Lifestyle study collected health service utilization and health-related expenditure data at the 2011–2012 follow-up surveys. Costing data were available for 4,409 participants. Unit costs for 2016–2017 were used where available or were otherwise inflated to 2016–2017 dollars. Age- and sex-adjusted costs per person were estimated using generalized linear models.

Results: The annual total direct cost ranged from $1,998 per person with normal weight to $2,501 per person with obesity in participants without diabetes. For those with diabetes, total direct costs were $2,353 per person with normal weight, $3,263 per person with overweight, and $3,131 per person with obesity. Additional expenditure as government subsidies ranged from $5,649 per person with normal weight and no diabetes to $8,085 per person with overweight and diabetes. In general, direct costs and government subsidies were higher for overweight and obesity compared to normal weight, regardless of diabetes status, but were more noticeable in the diabetes sub-group. The annual total excess cost compared with normal weight people without diabetes was 26% for obesity alone and 46% for those with obesity and diabetes.

Limitations: Participants included in this study represented a healthier cohort than the Australian population. The relatively small sample of people with both obesity and diabetes prevented a more detailed analysis by obesity class.

Conclusion: Overweight and obesity are associated with increased costs, which are further increased in individuals who also have diabetes. Interventions to prevent overweight and obesity or reduce weight in people who are overweight or obese, and prevent diabetes, should reduce the financial burden.     

The role of cognitive ability and personality traits for men and women in gift exchange outcomes

We examine the role of cognitive ability and personality traits in a gift exchange experiment. Controlling for cognitive ability and personality characteristics, men offer higher wages than women, and men and women with greater cognitive ability and greater agreeableness on the Big Five personality scale offer higher wages as well. Men provide greater effort than women do, and respond to higher wage rates with greater increases in effort. For both genders, one standard deviation increases in agreeableness and in wages generate similar increases in effort. Serious biases arise from omitting cognitive ability and pooling men and women.     

Integrated bio-economic models as tools to support land-use decision making: a review of potential and limitations

Bio-economic modelling has become a useful tool for anticipating the outcomes of policies and technologies before their implementation. Advances in mathematical programming have made it possible to build more comprehensive models. In an overview of recent studies about bio-economic models applied to land-use problems in agriculture and forestry, we evaluated how aspects such as uncertainty, multiple objective functions, system dynamics and time have been incorporated into models. We found that single objective models were more frequently applied at the farm level, while multiple objective modelling has been applied to meet concerns at the landscape level. Among the objectives, social aspects are seldom represented in all models, when being compared to economic and environmental aspects. The integration of uncertainty is occasionally a topic, while stochastic approaches are more frequently applied than non-stochastic robust methods. Most multiple-objective models do not integrate uncertainty or sequential decision making. Static approaches continue to be more recurrent than truly dynamic models. Even though integrating multiple aspects may enhance our understanding of a system; it involves a tradeoff between complexity and robustness of the results obtained. Land-use models have to address this balance between complexity and robustness in order to evolve towards robust multiple-objective spatial optimization as a prerequisite to achieve sustainability goals.     

Customer capabilities,switching costs,and bank performance

Customers develop switching costs when they invest time and effort to develop capabilities required to optimally use a given product. Such capabilities are likely to be firm specific and cannot be transferred perfectly to competitors' product offerings. Customers who face switching costs are likely to remain with the same firm and consume complementary products that meet their needs. Thus, firms can achieve competitive advantage by exploiting customers' switching costs. In this paper, we hypothesize that the extent to which firms can benefit from customers' switching costs is contingent upon the firms' internal cross‐selling capabilities. We use online banking data to test our hypotheses and find that customers' switching costs contribute to banks' profitability only in the presence of high levels of internal cross‐selling capabilities. Copyright © 2012 John Wiley & Sons, Ltd.     

The Innovation Value Chain in New Technology‐Based Firms: Evidence from the U.K.

Innovation is central to the survival and growth of firms, and ultimately to the health of the economies of which they are part. A clear understanding both of the processes by which firms perform innovation and the benefits which flow from innovation in terms of productivity and growth is therefore essential. This paper demonstrates the use of a conceptual framework and modeling tool, the innovation value chain (IVC), and shows how the IVC approach helps to highlight strengths and weaknesses in the innovation performance of a key group of firms—new technology‐based firms. The value of the IVC is demonstrated in showing the key interrelationships in the whole process of innovation from sourcing knowledge through product and process innovation to performance in terms of the growth and productivity outcomes of different types of innovation. The use of the IVC highlights key complementarities, such as that between internal R&D, external R&D, and other external sources of knowledge. Other important relationships are also highlighted. Skill resources matter throughout the IVC, being positively associated with external knowledge linkages and innovation success, and also having a direct influence on growth independent of the effect on innovation. A key benefit of the IVC approach is therefore its ability to highlight the roles of different factors at various stages of the knowledge–innovation–performance nexus, and to show their indirect as well as direct impact. This in turn permits both managerial and policy implications to be drawn.     

Value and risk in business-to-business e-banking

The purpose of this paper is to examine the role of risk in the formation of perceptions of value in the b2b domain, specifically within e-banking. The functional relationships between three types of risk (performance, financial and psychological) and the benefits and sacrifices components of value are tested within a broader nomological network that includes e-service quality (as an antecedent of value) and satisfaction, word-of-mouth and intention to switch (as outcomes of value). The hypothesised relationships are tested, using Partial Least Squares, on data collected through a postal survey from 167 UK-based SME organisations. The results confirm the significant but differential impact of the three types of risk on the two value components. Specifically performance risk and financial risk are found to be significant determinants of benefits, while psychological risk impacts on perceptions of sacrifices. We also provide evidence of the differential impact of the benefits and sacrifices components of value on satisfaction, and the existence of both direct and indirect (through satisfaction) impact of these components on word-of-mouth and intention to switch. This is the first documented empirical investigation of the impact of perceptions of risk in the study of perceptions of value within the domain of b2b marketing and consequently offers new insights into the subject matter. The theoretical and managerial implications of the findings are discussed and the manner in which the identified relationships can aid future research are explicated.     

Development through synergistic reforms

For many less developed countries production of high quality output is a precondition for firms to become exporters. Institutional deficiencies that raise costs of high quality production therefore limit the positive impact that trade facilitation can have on income. Consequently, institutional reforms that reduce costs of high quality production and trade reform have synergistic effects. In contrast, institutional reforms that reduce costs of low quality production (e.g., reforms that disproportionately benefit small businesses) interfere with the impact of trade reform. We obtain these results in a heterogeneous firm model that displays standard “industry rationalization” responses to reduced trade costs.     

Is power more evenly balanced in poor households?

The structure of intra-household allocation is crucial to know whether a transfer from a rich household to a poor one translates into a transfer from a rich individual to a poor one. If rich households are more unequal than poor ones, then a progressive transfer among households reduces intra-household inequality, hence inequality among individuals. More specifically, two conditions have to be satisfied for extending Generalized Lorenz judgments from household level to individual one. The fraction of the couple's expenditures devoted to goods jointly consumed should decrease at the margin with the couple's income as well as the part of private expenditure devoted to the disadvantaged individual. This double concavity condition is non-parametrically tested on the French Household Expenditure Survey (2000). It is not rejected by the data and supports the view that power is more evenly distributed in poor households.     

Did Vietnam veterans get sicker in the 1990s? The complicated effects of military service on self-reported health

The veterans disability compensation (VDC) program, which provides a monthly stipend to disabled veterans, is the third largest American disability insurance program. Since the late 1990s, VDC growth has been driven primarily by an increase in claims from Vietnam veterans, raising concerns about costs as well as health. We use the draft lottery to study the long-term effects of Vietnam-era military service on health and work in the 2000 Census. We find no evidence that military service affected overall employment rates or overall work-limiting disability rates (that is, health conditions that make work difficult). At the same time, military service sharply increased federal transfer income, especially for lower skilled white men, among whom there was also a large negative impact on employment and a marked increase in disability rates. The differential impact of Vietnam-era service on low-skilled men cannot be explained by more combat or war-theatre exposure for the least educated, because high school graduates were at least as likely to be exposed to combat or war theatre as the less-educated. This leaves the relative attractiveness of VDC for less-skilled men and the work disincentives embedded in the VDC system as a likely explanation for our findings.