Micro versus macro cointegration in heterogeneous panels

We consider the issue of cross-sectional aggregation in nonstationary and heterogeneous panels where each unit cointegrates. We derive asymptotic properties of the aggregate estimate, and necessary and sufficient conditions for cointegration to hold in the aggregate relationship. We then analyze the case when cointegration does not carry through the aggregation process, and we investigate whether the violation of the formal conditions for perfect aggregation can still lead to an aggregate equation that is observationally equivalent to a cointegrated relationship. We derive a measure of the degree of noncointegration of the aggregate relationship and we explore its asymptotic properties. We propose a valid bootstrap approximation of the test. A Monte Carlo exercise evaluates size and power properties of the bootstrap test.     

Economic burden of hospital malnutrition and the cost–benefit of supplemental parenteral nutrition in critically ill patients in Latin America

Abstract

Aim: Disease-related malnutrition (DRM) is a prevalent condition that significantly increases the risk of adverse outcomes in hospitalized patients, particularly those with critical illness. Limited data is available on the economic burden of DRM and the cost–benefit of nutrition therapy in high-risk populations in Latin America. The aims of the present study were to estimate the economic burden of DRM and evaluate the cost–benefit of supplemental parenteral nutrition (SPN) in critically ill patients who fail to receive adequate nutrient intake from enteral nutrition (EN) in Latin America.

Methods: Country-specific cost and prevalence data from eight Latin American countries and clinical data from studies evaluating outcomes in patients with DRM were used to estimate the costs associated with DRM in public hospitals. A deterministic decision model based on clinical outcomes from a randomized controlled study and country-specific cost data were developed to examine the cost–benefit of administering SPN to critically ill adults who fail to reach ≥60% of the calculated energy target with EN.

Results: The estimated annual economic burden of DRM in public hospitals in Latin America is $10.19 billion (range, $8.44 billion–$11.72 billion). Critically ill patients account for a disproportionate share of the costs, with a 6.5-fold higher average cost per patient compared with those in the ward ($5488.35 vs. $839.76). Model-derived estimates for clinical outcomes and resource utilization showed that administration of SPN to critically ill patients who fail to receive the targeted energy delivery with EN would result in an annual cost reduction of $10.2 million compared with continued administration of EN alone.

Limitations: The cost calculation was limited to the average daily cost of stay and antibiotic use. The costs associated with other common complications of DRM, such as prolonged duration of mechanical ventilation or more frequent readmission, are unknown.

Conclusions: DRM imposes a substantial economic burden on Latin American countries, with critically ill patients accounting for a disproportionate share of costs. Cost–benefit analysis suggests that both improved clinical outcomes and significant cost savings can be achieved through the adoption of SPN as a therapeutic strategy in critically ill patients who fail to receive adequate nutrient intake from EN.     

“Relative Importance of Risk Sources in Insurance Systems”, Edward W. Frees,April 1998

Abstract

This paper considers a Sparre Andersen collective risk model in which the distribution of the interclaim time is that of a sum of n independent exponential random variables; thus, the Erlang(n) model is a special case. The analysis is focused on the function φ(u), the expected discounted penalty at ruin, with u being the initial surplus. The penalty may depend on the deficit at ruin and possibly also on the surplus immediately before ruin. It is shown that the function φ(u) satisfies a certain integro-differential equation and that this equation can be solved in terms of Laplace transforms, extending a result found in Lin (2003). As a consequence, a closed-form expression is obtained for the discounted joint probability density of the deficit at ruin and the surplus just before ruin, if the initial surplus is zero. For this formula and other results, the roots of Lundberg’s fundamental equation in the right half of the complex plane play a central role. Also, it is shown that φ(u) satisfies Li’s (2003) renewal equation. Under the assumption that the penalty depends only on the deficit at ruin and that the individual claim amount density is a combination of exponential densities, a closed-form expression for φ(u) is derived. In this context, known results of the Cauchy matrix are useful. Surprisingly, certain results are best expressed in terms of divided differences, a topic deleted from the actuarial examinations at the end of last century.     

Does the ideal entrepreneurial team exist?

Up until now, studies on entrepreneurs and their relationship to business performance have focused primarily on analyzing the entrepreneur as an individual. While studies have been conducted on the entrepreneurial team, their focus has centered on team size and degree of diversity - cultural, age, gender - leaving a gap in the analysis of the effect of a team’s competencies on the outcome of the ventures. This research aims to help fill this gap by using the psychometric instrument DISC. This research analyzes entrepreneurship by opportunity, evaluating the performance of 109 Colombian companies and the composition of their entrepreneurial teams. The results obtained provide the basis for better understanding of the make-up of entrepreneurial teams, considering the variances and interdependencies of the competency development level among their members. They reveal that identifying the similarity or heterogeneity in certain groups of competencies, as well as how developed they are, can have an impact on the ventures’ success. The cluster analysis carried out suggests that highly developed competencies associated with the ‘dominance’ dimension in the members of an entrepreneurial team are essential. These must be above-average in heterogeneous levels among the team members. They must also be accompanied by the ‘steadiness’ competency provided by the team-oriented partners, as well as an average, homogeneous level of competencies associated with ‘conscientiousness’ if the new business is to achieve good financial results in its early years. The ‘influence’ dimension did not play a significant role. The teams made up of more homogeneous partners obtained the poorest financial results. Furthermore, the study provides new perspectives for measuring business performance in a venture, as well as for evaluating the relationships between the entrepreneurial team's competencies and the company’s results in the first years of business. Accordingly, it offers inputs for future research.

     

Kriging methodology for regional economic analysis: Estimating the housing price in Albacete

Because of the socioeconomic importance of the housing subsector in the local, regional, and national economy and its implications for housing policy, this paper attempts to analyze the spatial behavior of the free housing price in the city of Albacete. To achieve this aim, the authors have used the models and estimators imported from geology called kriging. To do this, it is necessary to know the spatial dependence structure of the process, which is shown in the variogram.