Qinan Wang

Nanyang Technological University | ntu · Division of Information Technology and Operations Management

Waiting has been a significant concern for healthcare services. We address this issue in the context of a two-tier service system in this study. A two-tier healthcare service system consists of two different service providers, typically one public service provider and one private service provider. In a baseline model, the two service providers are...

This study considers the echelon-stock (R,nT) policy for a single-item, two-stage serial inventory system. The main contribution is to first provide a method to exactly evaluate the expected inventory related cost and subsequently develop an approach to identify an optimal solution to minimize the long-run system cost.

We consider a distribution system consisting of a central warehouse and a group of retailers facing independent stochastic demand. The retailers replenish from the warehouse, and the warehouse from an outside supplier with ample supply. Time is continuous. Most previous studies on inventory control policies for this system have considered stock-bas...

We consider a time-based inventory control policy for a two-level supply chain with one warehouse and multiple retailers in this paper. Let the warehouse order in a fixed base replenishment interval. The retailers are required to order in intervals that are integer-ratio multiples of the base replenishment interval at the warehouse. The warehouse a...

We consider a decentralized supply chain, whereby a supplier sells a product to a group of independent buyers, and develop a strategy for the supplier to offer an all-units price discount or cash rebate for orders that are synchronized with its replenishments. As synchronized orders can be met with inventory directly from receiving to shipping with...

Although supply chain management has become an important management paradigm, the optimal control of a stochastic multi-echelon supply chain inventory system is still largely an open issue. An inventory control policy for such a system has to consider at least three aspects: order coordination, information sharing, and stock or risk pooling. Each a...

This article proposes an adaptive loss function (AL) control chart for statistical process control (SPC). This chart is able to monitor process shifts in the mean and variance simultaneously. It is appealing for its effectiveness in detecting process shifts and simplicity in operation under a computerized SPC environment. By using a fixed sample si...

The np control chart is used widely in Statistical Process Control (SPC) for attributes. It is difficult to design an np chart that simultaneously satisfies a requirement on false alarm rate and has high detection effectiveness. This is mainly because one is often unable to make the in-control Average Run Length ARL0 of an np chart close to a speci...

Supply chain management (SCM) has become an important management paradigm. As supply chain members are often separate and independent economic entities, a key issue in SCM is to develop mechanisms that can align their objectives and coordinate their activities so as to optimize system performance. In this paper, we provide a review of coordination...

This article proposes an algorithm for deploying manpower to a statistical process control (SPC) system that monitors a multistage manufacturing system. The algorithm minimizes the expected total cost by optimizing the amount of allocated manpower in the SPC system (referred to as an M-SPC system), as well as the sample sizes, sampling intervals an...

This paper presents an empirical study on the Lanchester model of combat for competitive advertising decisions. Three issues are evaluated: (i) the specification of the market share response model; (ii) the effect of inflation on the estimation of the response model; and (iii) the performance of competitive strategies. It is shown that (a) the squa...

When Statistical Process Control (SPC) deals with a quality characteristic that is a variable, it is usually necessary to monitor both the mean value and the variability. A CUSUM scheme comprising g cooperative CUSUM charts (called the g-CUSUM scheme) is more effective than the traditional Shewhart &S chart for this purpose. This article proposes a...

Little is known about the health preferences of Southeast Asians. The authors therefore investigated the feasibility of measuring health preferences of Chinese, Malays, and Indians in Singapore and compared their preference scores. A stratified random sample of the Singaporean general population was interviewed to measure preferences for a set of h...

ABSTRACTA challenge of supply chain management is to align the objectives, and hence coordinate the activities, of independent supply chain members. In this study, we approach this problem in a simple way by extending traditional quantity discounts that are based solely on buyers' individual order size to discount policies that are based on both bu...

Although quantity discount policies have been extensively analyzed, they are not well understood when there are many different buyers. This is especially the case when buyers face price-sensitive demand. In this paper we study a supplier's optimal quantity discount policy for a group of independent and heterogeneous retailers, when each retailer fa...

For many medical procedures, patients face substantial risk of complication or death when treatment is delayed. When a queue is formed in such a situation, it is imperative to assess the suffering and risk faced by patients in queue and plan adequate medical capabilities in advance to address the concerns. We develop in this paper a patient queue m...

Supply chain members can gain substantial benefits by coordinating their activities. However, a remaining challenge is to create useful coordination mechanisms when channel members are independent. This paper develops a coordination strategy with which a supplier uses quantity discounts to entice independent buyers to comply with an integer-ratio t...

In this paper, we evaluate the effectiveness of quantity discounts and volume discounts as coordination mechanisms in distribution channels with demand that is price-sensitive. We consider a single-vendor, single-retailer, distribution channel. Demand for the product arises only at the retailer. The demand faced by the retailer is assumed to be det...

The utility function for the Health Utilities Index Mark 2 (HUI2) system is based on preference measurements from a random sample of parents with exclusion of inconsistent respondents. Would results without exclusions or from a different group of parents have differed? Scores were obtained from parents of patients (n = 59) undergoing treatment for...

This study assesses the health-related quality-of-life (HRQL) effects of chorionic villi sampling (CVS) and genetic amniocentesis (GA), including both process and outcomes of prenatal diagnosis. The HRQL of 126 women participating in a randomized controlled clinical trial of CVS versus GA in Toronto and Hamilton, Ontario, was assessed in four inter...

Although the quantity discount problem has been extensively studied in the realm of a single supplier and a single buyer, it is not well understood when a supplier has many different buyers. This paper presents an analysis of a supplier's quantity discount decision when there are many buyers with different demand and cost structures. A common discr...

We study the coordination of a two-echelon distribution system where a vendor distributes a single product to a set of independent buyers. The problem is analyzed as a Stackelberg game in which the vendor acts as the leader and buyers act as followers. A simple strategy is developed for the vendor to employ a uniform quantity-discount policy to coo...

This paper proposes a differential game model of competitive advertising decisions for non-durable products by extending the Lanchester model and the Deal model of competitive advertising in the literature. The proposed model is compared empirically with the Lanchester model for model fitting and forecast accuracy. It is shown that the model is sui...

We consider the pricing and inventory decisions of a vendor who supplies a single product to multiple heterogeneous buyers. The problem is analyzed as a Stackelberg game in which the vendor acts as the leader by announcing its pricing policy to all the buyers in advance and the buyers act as followers by choosing their order quantity and the sassoc...

Objectives. To assess the health-related quality-of-life (HRQL) effects of chorionic villi sampling (CVS) and genetic amniocentesis (GA) prenatal diagnosis, including factors related to both the processes and the outcomes. Study Design. The HRQL of one hundred twenty six women participating in a randomized controlled clinical trial of CVS versus GA...

This paper presents an assessment of the health status of the Singaporean population by the Health Utilities Index (HUI) Mark 3 system. The HUI approach is a generic health status measure that uses a Multi-Attribute Health Status Classification (MAHSC) system. The assessment describes the health status of the population on eight aspects or dimensio...

The Health Utilities Index Mark 2 (HUI:2) is a generic multiattribute, preference-based system for assessing health-related quality of life. Health Utilities Index Mark 2 consists of two components: a seven-attribute health status classification system and a scoring formula. The seven attributes are sensation, mobility, emotion, cognition, self-car...

In this article, the bootstrap resampling methodology is used to set up the X̄ chart and R (or s) chart for SPC. The proposed algorithm allows the QA engineer to have more control on the design of the control charts via directly manipulating the Type I errors. As a result, the detecting power of the control charts has been increased while the Type...

We analyze the quantity discount problem by considering the competitive nature of the problem and the informational structure regarding the buyer’s cost structure. We formulate the problem as a two-person nonzero-sum game and analyze the seller’s optimal quantity discount schedule and the buyer’s optimal order quantity by using Stackelberg equilibr...

In this paper, we analyze discounting decisions for a supplier with a group of homogeneous customers. We focus on two aspects: the gaming nature of the discount problem and the demand consideration in the process. We use a general quantity discount schedule and start with the Stackelberg equilibrium of the problem. It is shown that, for the seller...

In this paper, we build a game theory model for a single-period inventory problem where each of three retailers tries to determine his optimal order quantity. Their products are substitutable and have random demands. Therefore, multiple direction demand transfers occur when one or more retailers are sold out. It is shown that, by using Nash equilib...

In the present paper, we give a brief review of static game models and their applications in management science. Our intention here is twofold: On the one hand, we would like to provide the reader with an overview of game theory and its applications in management science. On the other hand, we intent to explore the mathematical tractability of mana...

Apply the health utilities index (HUI) approach in population health measurement in Singapore.