Amr Arisha | Dublin Institute of Technology (original) (raw)

Papers by Amr Arisha

Abstract Purpose – The purpose of this paper is to analyse the concept of supply chain resilience... more Abstract
Purpose – The purpose of this paper is to analyse the concept of supply chain resilience (SCRES) within a concept mapping framework to seek conceptual clarity, with an emphasis on SCRES definitions, essential elements and managerial practices.
Design/methodology/approach – A systematic literature review was conducted of 103 peer-reviewed journal articles from the year 2000 to 2015, with the aim of answering a focus review question.
Findings – Through analysis and synthesis of the literature, the study revealed three major constructs used to define SCRES: phases of resilience, resilience strategies and the capabilities needed to be resilient. Emerging from the capabilities construct are five core SCRES capabilities: the ability to anticipate, to adapt, to respond, to recover and to learn. Also, given the need to consolidate the various constructs of SCRES, the study identified 13 essential elements and 84 managerial practices that support firms to achieve the five capabilities, which are then linked to SCRES strategies and phases to establish the connections that provide an integrated view of the concept.
Research limitations/implications – The explorative nature of this study and the role of the concept mapping framework, which does not empirically test the relationships in the model, are considered as limitations, to be addressed by the authors in future research.
Originality/value – The originality of this paper lies in the classification of different features of SCRES through a comprehensive concept mapping framework that establishes relationships and interactions between them. This study, therefore, lays a foundation for testing these connections in future empirical studies. The paper brings together fragmented literature from multiple studies to create a solid body of knowledge that addresses the need for conceptual clarity in SCRES literature.
Keywords Resilience, Supply-chain management, Systematic literature review
Paper type Literature review

Today's third level students are of a virtual generation, where online interactive multi-player g... more Today's third level students are of a virtual generation, where online interactive multi-player games, virtual reality and simulations are a part of everyday life, making gaming and simulation a very important catalyst in the learning process. Teaching methods have to be more innovative to help students understand the complexity of decisions within dynamic supply chain environment. Interactive simulation games have the potential to be an efficient and enjoyable means of learning. A serious interactive business game, Automobile Supply Chain Management Game (AUSUM), has been introduced in this paper. Using theories learnt in class as a knowledge base, participants have to develop effective supply chain partnership strategy to enhance their supply chain networks. Deploying the game over the web encourages student interaction and group work. Most importantly the game will enable students to fundamentally grasp the impact of strategic decisions on other parts and players of the supply chain network.

Emergency Medicine Journal, 2011

ABSTRACT The use of an interactive DES-based framework accurately determines the best simulation ... more ABSTRACT The use of an interactive DES-based framework accurately determines the best simulation scenarios and identifies the most effective ‘real-time’ strategies in improving PETs in an ED environment. Whilst increasing medical staffing or trolley numbers might seem intuitively beneficial to overall PETs, our ‘Virtual ED’ reveals that simply enforcing the national KPI 6-hour boarding limit for EDs, would have a greater impact on reducing PETs for all ED patients than increasing medical staff or assessment cubicles.. Before instigating potentially ineffectual and costly ‘real-time’ strategies, the construction of novel simulation scenarios in a ‘Virtual ED’ may allow implementation of more effective yet inexpensive bespoke alternatives.

Owing the fact that optimization of business process is a crucial requirement to navigate, surviv... more Owing the fact that optimization of business process is a crucial requirement to navigate, survive and even thrive in today's volatile business environment, this paper presents a framework for selecting a best-fit optimization package for solving complex business problems. Complexity level of the problem and/or using incorrect optimization software can lead to biased solutions of the optimization problem. Accordingly, the proposed framework identifies a number of relevant factors (e.g. decision variables, objective functions, and modeling approach) to be considered during the evaluation and selection process. Application domain, problem specifications, and available accredited optimization approaches are also to be regarded. A recommendation of one or two optimization software is the output of the framework which is believed to provide the best results of the underlying problem. In addition to a set of guidelines and recommendations on how managers can conduct an effective optimization exercise is discussed.

International Journal of Operational Research

In addition to the system’s complexity and uncertainty, healthcare managers face many challenges,... more In addition to the system’s complexity and uncertainty, healthcare managers face many challenges, including the increasing levels of demand and patient expectations at the time of more budget constraints enforced on healthcare service in Ireland. The delivery of a better patient care requires effective decision making especially in planning of healthcare resources. For an emergency department (ED) of a leading university hospital in the south of Dublin City, a decision support application for resource planning considering multiple performance indicators was developed. A comprehensive discrete event simulation model was used to identify the most significant variables and key factors that affect the ED performance. Combining this model with Taguchi orthogonal arrays and data envelopment analysis in an integrated manner helps to improve decision-making procedure in terms of systematic scenarios’ selection and evaluation. The developed system is used for resource planning and also to as...

European Journal of Operational Research, 2015

ABSTRACT Global population ageing is creating immense pressures on hospitals and other healthcare... more ABSTRACT Global population ageing is creating immense pressures on hospitals and other healthcare services, compromising their abilities to meet the growing demand from elderly patients. Current demand-supply gaps result in prolonged waiting times in emergency departments (EDs), and several studies have focused on improving ED performance. However, the overcrowding in EDs generally stems from delayed patient flows to inpatient wards - which are congested with inpatients waiting for beds in post-acute facilities. This problem of bed blocking in acute hospitals causes substantial cost burdens on hospitals. This study presents a system dynamics methodology to model the dynamic flow of elderly patients in the Irish healthcare system aimed at gaining a better understanding of the dynamic complexity caused by the system's various parameters. The model evaluates the stock and flow interventions that Irish healthcare executives have proposed to address the problem of delayed discharges, and ultimately reduce costs. The anticipated growth in the nation's demography is also incorporated in the model. Policy makers can also use the model to identify the potential strategic risks that might arise from the unintended consequences of new policies designed to overcome the problem of the delayed discharge of elderly patients.

ABSTRACT Non-linear processes within complex systems are difficult to predict. Using discrete eve... more ABSTRACT Non-linear processes within complex systems are difficult to predict. Using discrete event simulation (DES) models can be helpful for presenting the uncertainty level embedded within these processes. However, the interpretations of the resulting outcomes can be challenging to analyze. This is evident when experimenting with simulation models, and therefore requires the adaptation of existing models. Introducing cyclic entities such as interconnected resources to the simulation model adds a new level of complexity to the model. In practical cases, decision makers often demand a model that enables them to make quick decisions with less complexity involved. However, these individuals still want to be assured of a high degree of accuracy in the results. This article demonstrates how an analytical representation of complex DES models can be developed in order to facilitate prompt yet effective solutions for decision makers. This analytical representation provides a brief overview of the simulation results by using the staff scheduling and nurses’ utilization approaches. Results of the effective use of DES model and managers feedback are encouraging.

In today's competitive market, applying lean thinking provides supply chain the ability to produc... more In today's competitive market, applying lean thinking provides supply chain the ability to produce and deliver products in a timely and cost effective manner. To date, little research addressed lean distribution concept as an effective approach for improving supply chains. This caused a level of ambiguity regarding the concept's dimensional structure and its practices. This paper aims to explore the antecedents of lean distribution concept and identify its constructs and practices using a data driven analytical approach (i.e. exploratory factor analysis). Findings show that enhancing communication with customers, optimising transportation activity, people participating in problem solving procedures and increasing the reliability of distribution operations are critical dimensions of lean distribution paradigm.

High levels of complexity and uncertainty, and various sources of risks, create challenges for su... more High levels of complexity and uncertainty, and various sources of risks, create challenges for supply chain networks in achieving satisfactory performance, but advances in Information Technology can help supply chain decision makers predict the magnitude and impact of the risks related to their decisions. The framework proposed in this paper offers a solution that integrates intelligent-agents, simulation modelling, and optimisation. Its friendly, animated, interactive web-based interface is especially designed to engage the user in a 'serious game' environment. Each user plays a specific role in the supply chain network, and encounters the consequences of their decisions. The optimisation engine embedded in the framework advises users about the optimum decisions and their anticipated performance outcomes. Genetics Algorithm (GA) and Case-Based Reasoning (CBR) are used to enhance the decision quality. A high-level communication protocol has been designed, developed and implemented to facilitate client/server communications, and allow intelligent-agents to inter-communicate easily and efficiently. The tool we develop offers equal value in supporting management decision-making, or in educating trainees in the realities of supply chain management.

In response to global recession and increased competition, organizations have tried to become mor... more In response to global recession and increased competition, organizations have tried to become more efficient by decreasing costs and streamlining operations. To achieve this, the philosophy of lean management has gained in popularity. The main obstacle organizations face when implementing lean is deciding which activities to implement lean principals on. A well known lean practice, value stream mapping, is a very effective tool in mapping the current and future state of an organizations lean activities. Limitations in calculating variability information that describe system variations and uncertainty means more powerful analytical tools are needed. Simulation offers a more thorough analysis of a system's data, including the examination of variability and has the ability to change certain parameters and measure key lean performance indicators. Using a tire distribution company as a case study, this paper has developed a framework that uses discrete event simulation as an integrative layer between current and future value stream mapping. The framework maps current state value and non-value activities in the company and through simulation has highlighted the activities that should be used when developing the future state map. This paper has highlighted simulation as a crucial middle layer in value stream mapping that will generate more accurate future state maps than the more common practices of using random estimates and experience alone.

Owing the fact that optimization of business process is a crucial requirement to navigate, surviv... more Owing the fact that optimization of business process is a crucial requirement to navigate, survive and even thrive in today's volatile business environment, this paper presents a framework for selecting a best-fit optimization package for solving complex business problems. Complexity level of the problem and/or using incorrect optimization software can lead to biased solutions of the optimization problem. Accordingly, the proposed framework identifies a number of relevant factors (e.g. decision variables, objective functions, and modeling approach) to be considered during the evaluation and selection process. Application domain, problem specifications, and available accredited optimization approaches are also to be regarded. A recommendation of one or two optimization software is the output of the framework which is believed to provide the best results of the underlying problem. In addition to a set of guidelines and recommendations on how managers can conduct an effective optimization exercise is discussed.

Recently, the application of lean thinking in healthcare has grown significantly in response to r... more Recently, the application of lean thinking in healthcare has grown significantly in response to rising demand, caused by population growth, ageing and high expectations of service quality. However, insufficient justifications and lack of quantifiable evidence are the main obstacles to convince healthcare executives to adopt lean philosophies. This paper presents a real application of the successful implementation of a methodology that integrates Value Stream Mapping (VSM) and simulation modelling to improve an emergency department (ED) of a University hospital in Dublin. Appling lean approach in operations will minimize the patient waiting time and improve service time. VSM points out to the value-added and non-value-added activities in a clear schematic way. Simulation Model is also developed for the department in order to account for the variability and complexity resulted in healthcare processes due to dynamism and sharing resources. A comparative analysis of current and future state of the ED is provided and presented to managers to illustrate the potential benefits of adopting lean practices

This paper presents a case study of an Emergency Department of a public hospital in Dublin, and u... more This paper presents a case study of an Emergency Department of a public hospital in Dublin, and uses an integrated approach to determine optimal staffing levels to meet the challenges of its dynamic patient demand levels. A comprehensive stochastic model is developed to incorporate patients care pathways and the resources required along their treatment journeys. Analytical Hierarchical Process is utilised to enable decision makers to set their preferences for the facility's strategic objectives. Evolutionary algorithms are applied to optimise staff schedules. The resulted optimized schedules maintains continuity of care delivery for patients while ensuring a balanced equilibrium among available staff.

Timely access, prompt responses to patient needs, and availability of resources to deliver qualit... more Timely access, prompt responses to patient needs, and availability of resources to deliver quality service are the key priorities of healthcare systems, in particular hospitals. To cope with these constraints, healthcare managers have turned into lean thinking and approaches in their attempts to reduce non-value added activities and save costs by reducing wastes. This paper presents a case study of a private hospital in Dublin that used integrated approach of value stream mapping and simulation modeling to assess lean implementation in admission and discharge processes. Simulation enabled the strategic management to examine the outcomes of three possible improvement scenarios on hospital performance before implementing lean strategies. The proposed methodology helped to identify bottlenecks and non-value added procedures. Results analysis showed potential improvement in patients' admission and discharge cycle times, and offered the hospital the cost saving opportunity of reducing the numbers of bed required.

Proceedings of the Winter Simulation Conference 2014, 2014

ABSTRACT For system dynamics simulation (SD) models, an estimation of statistical distributions f... more ABSTRACT For system dynamics simulation (SD) models, an estimation of statistical distributions for uncertain parameters is crucial. These distributions could be used for testing models sensitivity, quality of policies, and/or estimating confidence intervals for these parameters. Assumptions related to normality, independence and constant variation are often misapplied in dynamic simulation. Bootstrapping holds a considerable theoretical advantage when used with non-Gaussian data for estimating empirical distributions for unknown parameters. Although it is a widely acceptable approach, it has had only limited use in system dynamics applications. This paper introduces an application of Direct Residual Bootstrapping (DRBS) for statistical inference in system dynamic model. DRBS has been applied successfully to 'The Irish Elderly Patient Delayed Discharge' dynamic model to estimate empirical distribution for some unknown parameters with a minimal computation effort. The computational results show that bootstrapping offers an efficient performance in cases of no availability of prior information of model parameters.

Abstract Purpose – The purpose of this paper is to analyse the concept of supply chain resilience... more Abstract
Purpose – The purpose of this paper is to analyse the concept of supply chain resilience (SCRES) within a concept mapping framework to seek conceptual clarity, with an emphasis on SCRES definitions, essential elements and managerial practices.
Design/methodology/approach – A systematic literature review was conducted of 103 peer-reviewed journal articles from the year 2000 to 2015, with the aim of answering a focus review question.
Findings – Through analysis and synthesis of the literature, the study revealed three major constructs used to define SCRES: phases of resilience, resilience strategies and the capabilities needed to be resilient. Emerging from the capabilities construct are five core SCRES capabilities: the ability to anticipate, to adapt, to respond, to recover and to learn. Also, given the need to consolidate the various constructs of SCRES, the study identified 13 essential elements and 84 managerial practices that support firms to achieve the five capabilities, which are then linked to SCRES strategies and phases to establish the connections that provide an integrated view of the concept.
Research limitations/implications – The explorative nature of this study and the role of the concept mapping framework, which does not empirically test the relationships in the model, are considered as limitations, to be addressed by the authors in future research.
Originality/value – The originality of this paper lies in the classification of different features of SCRES through a comprehensive concept mapping framework that establishes relationships and interactions between them. This study, therefore, lays a foundation for testing these connections in future empirical studies. The paper brings together fragmented literature from multiple studies to create a solid body of knowledge that addresses the need for conceptual clarity in SCRES literature.
Keywords Resilience, Supply-chain management, Systematic literature review
Paper type Literature review

Today's third level students are of a virtual generation, where online interactive multi-player g... more Today's third level students are of a virtual generation, where online interactive multi-player games, virtual reality and simulations are a part of everyday life, making gaming and simulation a very important catalyst in the learning process. Teaching methods have to be more innovative to help students understand the complexity of decisions within dynamic supply chain environment. Interactive simulation games have the potential to be an efficient and enjoyable means of learning. A serious interactive business game, Automobile Supply Chain Management Game (AUSUM), has been introduced in this paper. Using theories learnt in class as a knowledge base, participants have to develop effective supply chain partnership strategy to enhance their supply chain networks. Deploying the game over the web encourages student interaction and group work. Most importantly the game will enable students to fundamentally grasp the impact of strategic decisions on other parts and players of the supply chain network.

Emergency Medicine Journal, 2011

ABSTRACT The use of an interactive DES-based framework accurately determines the best simulation ... more ABSTRACT The use of an interactive DES-based framework accurately determines the best simulation scenarios and identifies the most effective ‘real-time’ strategies in improving PETs in an ED environment. Whilst increasing medical staffing or trolley numbers might seem intuitively beneficial to overall PETs, our ‘Virtual ED’ reveals that simply enforcing the national KPI 6-hour boarding limit for EDs, would have a greater impact on reducing PETs for all ED patients than increasing medical staff or assessment cubicles.. Before instigating potentially ineffectual and costly ‘real-time’ strategies, the construction of novel simulation scenarios in a ‘Virtual ED’ may allow implementation of more effective yet inexpensive bespoke alternatives.

Owing the fact that optimization of business process is a crucial requirement to navigate, surviv... more Owing the fact that optimization of business process is a crucial requirement to navigate, survive and even thrive in today's volatile business environment, this paper presents a framework for selecting a best-fit optimization package for solving complex business problems. Complexity level of the problem and/or using incorrect optimization software can lead to biased solutions of the optimization problem. Accordingly, the proposed framework identifies a number of relevant factors (e.g. decision variables, objective functions, and modeling approach) to be considered during the evaluation and selection process. Application domain, problem specifications, and available accredited optimization approaches are also to be regarded. A recommendation of one or two optimization software is the output of the framework which is believed to provide the best results of the underlying problem. In addition to a set of guidelines and recommendations on how managers can conduct an effective optimization exercise is discussed.

International Journal of Operational Research

In addition to the system’s complexity and uncertainty, healthcare managers face many challenges,... more In addition to the system’s complexity and uncertainty, healthcare managers face many challenges, including the increasing levels of demand and patient expectations at the time of more budget constraints enforced on healthcare service in Ireland. The delivery of a better patient care requires effective decision making especially in planning of healthcare resources. For an emergency department (ED) of a leading university hospital in the south of Dublin City, a decision support application for resource planning considering multiple performance indicators was developed. A comprehensive discrete event simulation model was used to identify the most significant variables and key factors that affect the ED performance. Combining this model with Taguchi orthogonal arrays and data envelopment analysis in an integrated manner helps to improve decision-making procedure in terms of systematic scenarios’ selection and evaluation. The developed system is used for resource planning and also to as...

European Journal of Operational Research, 2015

ABSTRACT Global population ageing is creating immense pressures on hospitals and other healthcare... more ABSTRACT Global population ageing is creating immense pressures on hospitals and other healthcare services, compromising their abilities to meet the growing demand from elderly patients. Current demand-supply gaps result in prolonged waiting times in emergency departments (EDs), and several studies have focused on improving ED performance. However, the overcrowding in EDs generally stems from delayed patient flows to inpatient wards - which are congested with inpatients waiting for beds in post-acute facilities. This problem of bed blocking in acute hospitals causes substantial cost burdens on hospitals. This study presents a system dynamics methodology to model the dynamic flow of elderly patients in the Irish healthcare system aimed at gaining a better understanding of the dynamic complexity caused by the system's various parameters. The model evaluates the stock and flow interventions that Irish healthcare executives have proposed to address the problem of delayed discharges, and ultimately reduce costs. The anticipated growth in the nation's demography is also incorporated in the model. Policy makers can also use the model to identify the potential strategic risks that might arise from the unintended consequences of new policies designed to overcome the problem of the delayed discharge of elderly patients.

ABSTRACT Non-linear processes within complex systems are difficult to predict. Using discrete eve... more ABSTRACT Non-linear processes within complex systems are difficult to predict. Using discrete event simulation (DES) models can be helpful for presenting the uncertainty level embedded within these processes. However, the interpretations of the resulting outcomes can be challenging to analyze. This is evident when experimenting with simulation models, and therefore requires the adaptation of existing models. Introducing cyclic entities such as interconnected resources to the simulation model adds a new level of complexity to the model. In practical cases, decision makers often demand a model that enables them to make quick decisions with less complexity involved. However, these individuals still want to be assured of a high degree of accuracy in the results. This article demonstrates how an analytical representation of complex DES models can be developed in order to facilitate prompt yet effective solutions for decision makers. This analytical representation provides a brief overview of the simulation results by using the staff scheduling and nurses’ utilization approaches. Results of the effective use of DES model and managers feedback are encouraging.

In today's competitive market, applying lean thinking provides supply chain the ability to produc... more In today's competitive market, applying lean thinking provides supply chain the ability to produce and deliver products in a timely and cost effective manner. To date, little research addressed lean distribution concept as an effective approach for improving supply chains. This caused a level of ambiguity regarding the concept's dimensional structure and its practices. This paper aims to explore the antecedents of lean distribution concept and identify its constructs and practices using a data driven analytical approach (i.e. exploratory factor analysis). Findings show that enhancing communication with customers, optimising transportation activity, people participating in problem solving procedures and increasing the reliability of distribution operations are critical dimensions of lean distribution paradigm.

High levels of complexity and uncertainty, and various sources of risks, create challenges for su... more High levels of complexity and uncertainty, and various sources of risks, create challenges for supply chain networks in achieving satisfactory performance, but advances in Information Technology can help supply chain decision makers predict the magnitude and impact of the risks related to their decisions. The framework proposed in this paper offers a solution that integrates intelligent-agents, simulation modelling, and optimisation. Its friendly, animated, interactive web-based interface is especially designed to engage the user in a 'serious game' environment. Each user plays a specific role in the supply chain network, and encounters the consequences of their decisions. The optimisation engine embedded in the framework advises users about the optimum decisions and their anticipated performance outcomes. Genetics Algorithm (GA) and Case-Based Reasoning (CBR) are used to enhance the decision quality. A high-level communication protocol has been designed, developed and implemented to facilitate client/server communications, and allow intelligent-agents to inter-communicate easily and efficiently. The tool we develop offers equal value in supporting management decision-making, or in educating trainees in the realities of supply chain management.

In response to global recession and increased competition, organizations have tried to become mor... more In response to global recession and increased competition, organizations have tried to become more efficient by decreasing costs and streamlining operations. To achieve this, the philosophy of lean management has gained in popularity. The main obstacle organizations face when implementing lean is deciding which activities to implement lean principals on. A well known lean practice, value stream mapping, is a very effective tool in mapping the current and future state of an organizations lean activities. Limitations in calculating variability information that describe system variations and uncertainty means more powerful analytical tools are needed. Simulation offers a more thorough analysis of a system's data, including the examination of variability and has the ability to change certain parameters and measure key lean performance indicators. Using a tire distribution company as a case study, this paper has developed a framework that uses discrete event simulation as an integrative layer between current and future value stream mapping. The framework maps current state value and non-value activities in the company and through simulation has highlighted the activities that should be used when developing the future state map. This paper has highlighted simulation as a crucial middle layer in value stream mapping that will generate more accurate future state maps than the more common practices of using random estimates and experience alone.

Owing the fact that optimization of business process is a crucial requirement to navigate, surviv... more Owing the fact that optimization of business process is a crucial requirement to navigate, survive and even thrive in today's volatile business environment, this paper presents a framework for selecting a best-fit optimization package for solving complex business problems. Complexity level of the problem and/or using incorrect optimization software can lead to biased solutions of the optimization problem. Accordingly, the proposed framework identifies a number of relevant factors (e.g. decision variables, objective functions, and modeling approach) to be considered during the evaluation and selection process. Application domain, problem specifications, and available accredited optimization approaches are also to be regarded. A recommendation of one or two optimization software is the output of the framework which is believed to provide the best results of the underlying problem. In addition to a set of guidelines and recommendations on how managers can conduct an effective optimization exercise is discussed.

Recently, the application of lean thinking in healthcare has grown significantly in response to r... more Recently, the application of lean thinking in healthcare has grown significantly in response to rising demand, caused by population growth, ageing and high expectations of service quality. However, insufficient justifications and lack of quantifiable evidence are the main obstacles to convince healthcare executives to adopt lean philosophies. This paper presents a real application of the successful implementation of a methodology that integrates Value Stream Mapping (VSM) and simulation modelling to improve an emergency department (ED) of a University hospital in Dublin. Appling lean approach in operations will minimize the patient waiting time and improve service time. VSM points out to the value-added and non-value-added activities in a clear schematic way. Simulation Model is also developed for the department in order to account for the variability and complexity resulted in healthcare processes due to dynamism and sharing resources. A comparative analysis of current and future state of the ED is provided and presented to managers to illustrate the potential benefits of adopting lean practices

This paper presents a case study of an Emergency Department of a public hospital in Dublin, and u... more This paper presents a case study of an Emergency Department of a public hospital in Dublin, and uses an integrated approach to determine optimal staffing levels to meet the challenges of its dynamic patient demand levels. A comprehensive stochastic model is developed to incorporate patients care pathways and the resources required along their treatment journeys. Analytical Hierarchical Process is utilised to enable decision makers to set their preferences for the facility's strategic objectives. Evolutionary algorithms are applied to optimise staff schedules. The resulted optimized schedules maintains continuity of care delivery for patients while ensuring a balanced equilibrium among available staff.

Timely access, prompt responses to patient needs, and availability of resources to deliver qualit... more Timely access, prompt responses to patient needs, and availability of resources to deliver quality service are the key priorities of healthcare systems, in particular hospitals. To cope with these constraints, healthcare managers have turned into lean thinking and approaches in their attempts to reduce non-value added activities and save costs by reducing wastes. This paper presents a case study of a private hospital in Dublin that used integrated approach of value stream mapping and simulation modeling to assess lean implementation in admission and discharge processes. Simulation enabled the strategic management to examine the outcomes of three possible improvement scenarios on hospital performance before implementing lean strategies. The proposed methodology helped to identify bottlenecks and non-value added procedures. Results analysis showed potential improvement in patients' admission and discharge cycle times, and offered the hospital the cost saving opportunity of reducing the numbers of bed required.

Proceedings of the Winter Simulation Conference 2014, 2014

ABSTRACT For system dynamics simulation (SD) models, an estimation of statistical distributions f... more ABSTRACT For system dynamics simulation (SD) models, an estimation of statistical distributions for uncertain parameters is crucial. These distributions could be used for testing models sensitivity, quality of policies, and/or estimating confidence intervals for these parameters. Assumptions related to normality, independence and constant variation are often misapplied in dynamic simulation. Bootstrapping holds a considerable theoretical advantage when used with non-Gaussian data for estimating empirical distributions for unknown parameters. Although it is a widely acceptable approach, it has had only limited use in system dynamics applications. This paper introduces an application of Direct Residual Bootstrapping (DRBS) for statistical inference in system dynamic model. DRBS has been applied successfully to 'The Irish Elderly Patient Delayed Discharge' dynamic model to estimate empirical distribution for some unknown parameters with a minimal computation effort. The computational results show that bootstrapping offers an efficient performance in cases of no availability of prior information of model parameters.