Bootstrap prediction regions for multivariate autoregressive processes

Two new methods for improving prediction regions in the context of vector autoregressive (VAR) models are proposed. These methods, which are based on the bootstrap technique, take into account the uncertainty associated with the estimation of the model order and parameters. In particular, by exploiting an independence property of the prediction error, we will introduce a bootstrap procedure that allows for better estimates of the forecasting distribution, in the sense that the variability of its quantile estimators is substantially reduced, without requiring additional bootstrap replications. The proposed methods have a good performance even if the disturbances distribution is not Gaussian. An application to a real data set is presented.     

Italian corporate foundations and the challenge of multiple stakeholder interests

This article investigates corporate foundations, a specific expression of corporate philanthropy that is narrowly considered in the literature. We aim to verify whether the interests of the founder firm are significant antecedents of the model, activities, and issues addressed by the related foundation. Data were collected through a survey of seventy Italian corporate foundations, representing 59.8 percent of the total number of such foundations based in Italy. The analysis identified three clusters of corporate foundations—granter, expert, and edifier. Research demonstrates that through these clusters, the interests pursued by founder firms have a significant influence on integration between firms and corporate foundations and on the foundations' activities.     

Satisficing in strategic environments: A theoretical approach and experimental evidence

The satisficing approach is generalized and applied to finite n-person games. We formally define the concept of satisficing and propose a theory that allows satisficing players to make “optimal” decisions without being equipped with any prior. We also review some experiments on strategic games illustrating and partly supporting our theoretical approach.     

An experimental study of the generosity game

We study ultimatum and dictator variants of the generosity game. In this game, the first mover chooses the amount of money to be distributed between the players within a given interval, knowing that her own share is fixed. Thus, the first mover is not confronted with the typical trade-off between her own and the other’s payoff. For each variant of the game, we study three treatments that vary the range of potential pie sizes so as to assess the influence of these changes on the first movers’ generosity. We find that removing the trade-off inspires significant generosity, which is not always affected by the second mover’s veto power. Moreover, the manipulation of the choice set indicates that choices are influenced by the available alternatives.     

Life Expectancy,Schooling, and Lifetime Labor Supply: Theory and Evidence Revisited

This paper presents a theoretical and empirical analysis of the role of life expectancy for optimal schooling and lifetime labor supply. The results of a simple prototype Ben‐Porath model with age‐specific survival rates show that an increase in lifetime labor supply is not a necessary, or a sufficient, condition for greater life expectancy to increase optimal schooling. The observed increase in survival rates during working ages that follows from the “rectangularization” of the survival function is crucial for schooling and labor supply. The empirical results suggest that the relative benefits of schooling have been increasing across cohorts of U.S. men born between 1840 and 1930. A simple quantitative analysis shows that a realistic shift in the survival function can lead to an increase in schooling and a reduction in lifetime labor hours.     

Partial cell suppression: A new methodology for statistical disclosure control

In this paper we address the problem of protecting confidentiality in statistical tables containing sensitive information that cannot be disseminated. This is an issue of primary importance in practice. Cell Suppression is a widely-used technique for avoiding disclosure of sensitive information, which consists in suppressing all sensitive table entries along with a certain number of other entries, called complementary suppressions. Determining a pattern of complementary suppressions that minimizes the overall loss of information results into a difficult (i.e., -hard) optimization problem known as the Cell Suppression Problem. We propose here a different protection methodology consisting of replacing some table entries by appropriate intervals containing the actual value of the unpublished cells. We call this methodology Partial Cell Suppression, as opposed to the classical complete cell suppression. Partial cell suppression has the important advantage of reducing the overall information loss needed to protect the sensitive information. Also, the new method provides automatically auditing ranges for each unpublished cell, thus saving an often time-consuming task to the statistical office while increasing the information explicitly provided with the table. Moreover, we propose an efficient (i.e., polynomial-time) algorithm to find an optimal partial suppression solution. A preliminary computational comparison between partial and complete suppression methologies is reported, showing the advantages of the new approach. Finally, we address possible extensions leading to a unified complete/partial cell suppression framework.     

Linking global value chains and supply chain management: evidence from the electric motors industry

The global value chain (GVC) framework and its central concept of governance are increasingly advocated as powerful tools for interpreting managerial issues with particular reference to global supply chain (SC) management. However, a gap still exists about how the GVC concepts, which have been developed at the industry level, can be applied at the company level. The aim of this work is therefore to investigate how the concepts of GVC structure and governance are related to the way the SC is managed. Several research propositions drawn from the literature are investigated by means of seven case studies in the electric motors industry. The results show that the GVC can be a useful framework for understanding and deploying SC management at the company level. Moreover, the analysis of the governance modes provides an effective tool to explain the existing degree of technological and operational collaboration in the SC. Finally, we show the importance of considering such contextual factors as company size and the competitive priorities of the company to move seamlessly between the GVC, at the industry level, and SC management, at the company level.     

Study of the association between gait variability and physical activity

Background

Gait variability can be considered an indirect measure of gait stability, in particular regarding temporal or spatial variability assessment. Physical activity, such as walking, is advised for the elderly and can be improved by gait stability. The aim of this study was to investigate the associations between gait stability and physical activity in women of different age ranges.

Methods

Forty-two healthy women of different age ranges (18-40 yrs. and 65-75 yrs.) were recruited in the study. To assess physical activity, the subjects wore a multi-sensor activity monitor for a whole week, inferring the time spent in moderate to vigorous physical activity (MVPA). MVPA were analysed in bouts of at least 10 subsequent minutes (MVPA_bouts) and in overall minutes (MVPA_tot). A kinematic analysis was performed with an optoelectronic system to calculate gait variability - expressed as standard deviation (SD) and coefficient of variability (CV) of step width, stride length, stance and swing time (during treadmill walking at different speeds).

Results

Elderly women, with high walking speed (5 km/h), and moderate step width variability (CV = 8–27%), met the recommended levels of physical activity (MVPA_tot and MVPA_bouts). Furthermore, gait variability, adjusted for age and number of falls, was significantly and negatively associated with MVPA_tot only at 3.5 km/h, and with MVPA_bouts only at 4 km/h.

Conclusions

In a population of healthy elderly women, gait variability was significantly and negatively associated with the level of physical activity. Healthy elderly women, with moderate gait variability (step width variability), and high preferred walking speed, seem to be able to meet the recommended levels of physical activity.

     

Performance and risk management

Abstract

Performance and risk management are seen by some as two ends of the same spectrum. Performance measurement and management is about steering an enterprise towards a profitable and viable future, whilst risk management is about avoiding the pitfalls that can overwhelm and ultimately put an enterprise out of business. But should the functions and processes of performance measurement and management be integrated with those of risk management? What are the consequences of this integration? How should this be done in practice? In this editorial we briefly chart the debate between those who propose it is important to keep the functions separate and those who advocate integration before presenting the empirical research that informs this conversation.