Ambulance allocation for maximal survival with heterogeneous outcome measures

This paper proposes new models for locating emergency medical services (EMS) by incorporating survival functions for capturing multiple-classes of heterogeneous patients. The Maximal Expected Survival Location Model for Heterogeneous Patients (MESLMHP) aims to maximize the overall expected survival probability of multiple-classes of patients, whereby different classes could be defined according to agreed patient categories based on response time targets, or by capturing differing medical conditions each with a corresponding survival function. Furthermore, we propose and demonstrate an approximation approach to solving the extended stochastic version of MESLMHP, which utilizes queuing theory to permit the modeling of congestion and utilization at each ambulance station, and does not require assumptions to be made on the utilization of ambulances. Both models are demonstrated using data from the ambulance service in Wales. We show that our multiple outcome measures and survival-maximizing approach, rather than one based on average response time targets alone or a single patient class provides more effective EMS ambulance allocations.     

The heritability of emergent leadership: Age and gender as moderating factors

In this study, we examined the moderating influences of gender and age with respect to testing the heritability of leadership emergence. A large data base of 12,112 twins from Sweden was used in the current study to decompose the variance of emergent leadership into an unobservable genetic component and environmental components that are either common or unshared among twin pairs. Consistent with prior leadership research on genetics, we found that a genetic factor is able to explain a significant proportion of the variation across individuals in predicting how twins perceive their emergent leadership behavior (about 44% for women and 37% for men). Furthermore, we also found that the magnitude of genetic influence on emergent leadership varied with age, but only for women with the heritability estimate being highest for the mid-age women versus lowest for the older women. Implications for advancing research on the genetic and environmental influences on leadership emergence are discussed.     

Exploring the role of supervisor trust in the associations between multiple sources of relationship conflict and organizational citizenship behavior

We develop and test a model that builds directly on social exchange theory to predict different roles for supervisor trust in the relationships between organizational citizenship behavior and relationship conflict occurring between supervisors and subordinates and between peers. Specifically, we posit that the association between citizenship behavior and relationship conflict between employees and supervisors is mediated by supervisor trust, while the association between citizenship behaviors and relationship conflict occurring between peers is moderated by supervisor trust. We test our dual role for supervisor trust in a field study of 160 supervisor–employee dyads. Results support the different roles played by supervisor trust. We close by discussing the implications of our results for theory and practice in the relationship conflict and citizenship domains.     

A comparative study of three leadership approaches in India

We examined the validity of three leadership approaches in an organization in India. We used a multi-theory and multi-method design to competitively test transformational leadership theory, the nurturant–task leadership model, and a local organization-specific leadership model. Transformation leadership theory is one of the most widely studied and accepted theories in Western countries and is viewed as a universalistic leadership approach. The nurturant–task leadership model was developed in India and viewed as a culture-specific leadership approach. We also developed a local leadership model, called RDO, a pseudonym for the organization, and viewed it as an organization-specific leadership approach, using a qualitative analysis of interview data. The overall results of our qualitative–quantitative work provide strong support for the RDO leadership model, some support for a nurturant–task leadership model, and minimal support for transformational leadership theory. These results suggest that research designs that include a multi-theory, multi-methods approach in a single culture have the potential to increase our understanding of leadership processes.     

A Service Provider's Elicitation of Its Customers’ Demand Distributions by a Price Mechanism

In a service environment a service provider needs to determine the amount and kinds of capacity to meet customers’ needs over many periods. To make good decisions, she needs to know the probability distribution of her customers’ demand in each period. We study a situation in which customers’ demand for a given service is random in each period, but inelastic, or modeled well by this assumption, and cannot be delayed to the next period. This article presents a mechanism that allows a service provider to learn the distribution of a customer's demand by offering him a set of contracts through which he can partially prepay for future service for a reduced cost for units of service based on anticipated needs. We describe the form of a set of contracts that will cause the customer to reveal his demand distribution as he minimizes his expected costs. To justify the effort of organizing and offering contracts, we present an application that demonstrates the cost savings to the service provider with better capacity planning using the truthfully elicited distribution.     

AN INTERNATIONAL COMPARISON OF LIFETIME INEQUALITY: HOW CONTINENTAL EUROPE RESEMBLES NORTH AMERICA

We compare earnings inequality and mobility across the United States, Canada, France, Germany and the United Kingdom during the late 1990s. A flexible model of earnings dynamics that isolates positional mobility within a stable earnings distribution is estimated. Earnings trajectories are then simulated, and lifetime annuity value distributions are constructed. Earnings mobility and employment risk are found to be positively correlated with base‐year inequality. Taken together they produce more equalization in countries with high cross‐section inequality such that the countries in our sample have more similar lifetime inequality levels than cross‐section measures suggest.     

Inventory Policy with Parametric Demand: Operational Statistics,Linear Correction,and Regression

In this paper, we consider data‐driven approaches to the problem of inventory control. We first consider the approach of operational statistics and review related results which enable us to maximize a priori expected profit uniformly over all parameter values, when the demand distribution is known up to the location and scale parameters. For the case of the unknown shape parameter, we first suggest a heuristic approach based on operational statistics to obtain improved ordering policies and illustrate the same for the case of a Pareto demand distribution. In more general cases where the heuristic is not applicable, we suggest linear correction and support vector regression approaches to better estimate ordering policies, and illustrate these using a Gamma demand distribution. In certain cases, our proposed approaches are found to yield significant improvements.     

The max quasi-independent set problem

In this paper, we deal with the problem of finding quasi-independent sets in graphs. This problem is formally defined in three versions, which are shown to be polynomially equivalent. The one that looks most general, namely, f-max quasi-independent set, consists of, given a graph and a non-decreasing function f, finding a maximum size subset Q of the vertices of the graph, such that the number of edges in the induced subgraph is less than or equal to f(|Q|). For this problem, we show an exact solution method that runs within time O^*(2^{\fracd-27/23d+1n})O^{*}(2^{\frac{d-27/23}{d+1}n}) on graphs of average degree bounded by d. For the most specifically defined γ-max quasi-independent set and k-max quasi-independent set problems, several results on complexity and approximation are shown, and greedy algorithms are proposed, analyzed and tested.     

Entrepreneurial orientation and the business performance of SMEs: a quantitative study from the Netherlands

Entrepreneurial Orientation (EO) is often mentioned as an antecedent of growth, competitive advantage and superior performance, and prior empirical research has often shown a positive relationship between EO and performance appears to exist. However, an important question that remains unanswered is what effect EO might have on firm performance during periods of economic crisis, and the severe environmental turbulence that accompany such crises. This research is a first investigation towards the effects of EO on the performance of small and medium sized firms during the current global economic crisis. In this study we use the multidimensional model of EO and test a series of hypotheses pertaining to its performance effects using survey data gathered from 164 Dutch SMEs. The present research shows that proactive firm behavior positively contributes to SME performance during the economic crisis. We further show that innovative SMEs do perform better in turbulent environments, but those innovative SMEs should minimize the level of risk and should take action to avoid projects that are too risky.     

A real option theoretic fuzzy evaluation model for enterprise resource planning investment

The high failure rate of ERP implementation is due to a common pitfall that ERP projects are often enacted as merely investment into installation of IT infrastructure, rather than systematic planning of operation changes, business process re-engineering and a paradigm shift for the operation and management. To manage ERP investment in a changing environment for high payoff, this paper adopts a real option theoretic method. Fuzzy payoff valuation is introduced to deal with uncertainties in order to minimize the risk of failure. The proposed ERP evaluation model is geared towards small and medium enterprises. A case study is presented to validate the proposed fuzzy real options. The results indicate the potential of modeling ERP investment as “Expand”, “Contain” and “Abandon” options in different scenarios. The fuzzy real option model bestows a novel ex-ante cost analysis for justifying ERP investment in the implementation cycle.