Identifying inventory project management conflicts: Results of an empirical study
شناسایی تضادهای مدیریت پروژه موجود : نتایج یک مطالعه تجربی-2020
Although conflicts are being studied in many different management fields there seems to be a rather restricted number of studies on inventory management-related conflicts and it is for this reason why we conducted a study on exploring the different types of conflicts, their causes and the emerging character of conflicts during the shaping, implementation and usage of inventory systems. In doing so, a framework for assessing different types of conflicts is taken as a starting point. From our case studies, it can be concluded that each of the archetypical conflicts addressed in our framework manifested itself in the companies studied. Our exploratory case studies strongly indicates that during the process of redesigning and implementing improvements inventory management conflicts can evolve in time. Furthermore, in almost all companies studied, the identified conflicts had a multidimensional character and were a mix of the archetypes addressed in our theoretical framework. For project managers it seems to be important to be aware of the different potential conflicts that might arise during the course of inventory projects. The results presented in this article may therefore help project managers to guide projects in the area of inventory management more effectively.
Keywords: Inventory management | Conflicts | Case study | Typology | Stakeholders
Product assortment and space allocation strategies to attract loyal and non-loyal customers
مجموعه ای از محصولات و استراتژی های تخصیص فضا برای جذب مشتری های وفادار و غیر وفادار-2020
Assortment planning deserves much attention from practitioners and academics due to its direct impact on retailers’ commercial success. In this paper we focus on the increasingly popular retail practice to use combined product assortments with both “standard”and more fashionable and short-lived “variable”products for building up store traffic of “loyal”and “non-loyal”heterogeneous customers and enlarging the sales due to the potential cross-selling effect. Addressing the assortment planning as a bilevel optimization problem, we focus on decision-dependent uncertainties: the retailer’s binary decision about product inclusion influences the distribution of the product’s demand. Furthermore, our model accounts for customers’ optimal purchase quantities, which depend on budget constraints limiting the basket that a customer is able to purchase. We propose iterative heuristics using optimal quantization of demand and customers budget distributions to define the total assortment and the inventory level per product. These heuristics provide lower bounds on the optimal value. We conduct a comparison to other existing lower bounds and we formulate upper bounds via linear (LP) and semidefinite (SDP) relaxations for the performance evaluation of the heuristics and for an efficient numerical solution in high-dimensional cases. For managerial insights, we compare the proposed approach with three assortment planning strategies: (1) the retailer does not carry variable products; (2) the retailer ignores the cross-selling effect; and (3) the maximum space allocated to each product is fixed. Our results suggest that variable assortment boosts the retailers profits if the cross-selling effect is not neglected in the decision about products quan- tities.
Keywords: OR in marketing | Assortment planning | Inventory management | Bilevel optimization | Stochastic optimization
In search of the negative relationship between product variety and inventory turnover
در جستجوی رابطه منفی بین تنوع محصول و گردش موجودی-2020
Inventory management literature suggests that product variety may negatively affect inventory turnover. However, little empirical evidence exists to support such a relationship. Inventory turnover is the ratio of sales to inventory, thus, the impact of product variety on both sales and inventory should be considered. Marketing literature indicates that increased product variety helps to increase sales, whereas operations management literature proposes that increased product variety leads to higher inventory levels due to a loss of risk pooling. Given that increased product variety leads to higher sales and higher inventory levels, the change in the ratio of sales to inventory (inventory turnover) in response to increased product variety is unclear theoretically and therefore more of an empirical question. In this study, we explore the impact of product variety on inventory turnover using a balanced panel data set. We find that, in general, product variety negatively affects inventory turnover, but this negative impact may disappear when demand variability is low. Our findings provide an explanation for the lack of conclusive empirical evidence supporting the negative influence of product variety on inventory turnover. Product variety may be found not to negatively affect inventory turnover as it may have a similar influence on sales and inventory levels when demand variability is low. The study also offers managerial suggestions on product variety decisions and inventory management.
Keywords: Inventory theory | Inventory turnover | Product variety | Demand variability
Bachelor of pharmacy graduates perceptions of the pharmacy administration curriculum in Trinidad and Tobago
برداشت کارشناسی فارغ التحصیلان داروسازی از برنامه درسی مدیریت داروخانه در ترینیداد و توباگو-2020
As the profession of pharmacy has evolved, pharmacy education has developed to include competencies and skills related to pharmacy administration services. Competencies taught in pharmacy administration courses are expected to provide graduates with skills to effectively undertake administrative functions. Our study aimed to assess perceptions about knowledge and skills gained by the pharmacists during the Pharmacy Administration course at the School of Pharmacy, the University of the West Indies (UWI), Trinidad and Tobago. Methods: A cross-sectional survey was carried out among pharmacists working in hospitals and community pharmacies in Trinidad using non-probability convenience sampling. A structured questionnaire was distributed to 262 pharmacists who completed the Pharmacy Administration course. Two-hundred eighteen (83%) usable responses were included for analysis. Results: Many (45.4%) respondents agreed that the course provided them with the knowledge of running a business, 78% said they were able to apply the skills in their practice, and 80% mentioned that the course should be mandatory. Pharmacists found that the course on business management enhanced their knowledge in the fields of managing human resources, conflict management, marketing, project management, corporate turnaround, inventory, and financial management. Conclusions: The Pharmacy Administration course in the bachelor of science degree in pharmacy programme at the School of Pharmacy, UWI remains relevant in the areas of marketing, human resource management, and inventory management. The programme can be extended to a full time masters course to interested pharmacy graduates.
Keywords: Pharmacy administration | Curriculum | Trinidad | Pharmacists
On the multi-product newsvendor with bounded demand distributions
روزنامه فروش چند محصولی با توزیع های محدود تقاضا-2018
We consider a multi-item newsvendor problem with side constraints and common continuous demand distributions that are bounded implying that the items’ profit functions are nondifferentiable. In particular we focus on the cases of uniform and triangular distributions. These distributions naturally describe demand that is guaranteed to exceed a certain threshold – for example, consumption of basic food products or electric power consumption over any given day. Moreover, in practice, it is often difficult to estimate the demand distribution. Accordingly, the uniform and triangular distributions become default modeling choices when only information regarding the bounds and possibly the mode of the distribution is known. We generalize a previous quadratic programming model for uniformly distributed demand on to allow a to be nonzero and to allow the order quantity to be smaller than a. We study the corrected model and propose an efficient algorithm for determining an optimal solution. The algorithm is motivated by a structural result of an upper bound on the number of guaranteed shortage products, which typically appear in multiproduct settings with a positive demand distribution lower bound. The performance of our specialized algorithm is compared to that achieved when solving our formulation with a piecewise quadratic objective using a state-of-the-art standard solver. We also extend the modeling technique to propose a nonlinear programming formulation for triangular demand distributions. A similar approach can be adopted to approximate other demand distributions with a possibly non-finite support, such as truncated normal with strictly positive lower bounds.
keywords: Logistics |Inventory management |Multi-item newsvendor |Quadratic programming |Convex programming
Optimal production-sales policies and entry time for successive generations of new products
سیاست های بهینه تولید - فروش و زمان ورود برای نسل های بعدی محصولات جدید-2018
This paper explores the optimal initial inventory at launch, sales plan, and introduction time for a new generation of a product. We propose a multi-generation demand model that accounts for supply constraints. A mathematical model of the supply-restricted multi-generation diffusion problem is then developed and the optimal sales policy is derived. Closed-form analytical expressions as well as numerical experiments are used to investigate the effect of consumers backlogging, cost of production capacity, unit profit margin for the products, market expansion by the new generation, and cannibalization of older generations. Through consideration of supply restrictions and lost sales, we are able to generalize previous findings on market entry policy by showing that there is a continuous range of optimal introduction times. We show that the inter-dependence between production capacity and initial inventory varies based on the introduction time of the new generation. We also provide an application of the proposed model in the case of Sonys PlayStation®3 game console. The results suggest that the company introduced the product too late and overproduced inventory which, as supported by empirical evidence, had a negative impact on the products performance. Limitations and considerations for the application of the model are also discussed.
keywords: Production and inventory management |Myopic and build-up policies |Market entry timing |Multi-generation innovation diffusion |PlayStation®3 game console
The impact of abusing return policies: A newsvendor model with opportunistic consumers
تاثیر سوء استفاده از سیاست های بازگشتی: یک مدل روزنامه فروشی با مشتری های فرصت طلب-2018
Consumers may return a product for a variety of reasons, such as the product having the wrong color or size, having poor functionality, being damaged during shipment, or simply prompting regret for an impulsive purchase. Retailers generally provide lenient return policies not only because they may signal high quality but also because they act as risk relievers for consumers’ purchasing decision processes. However, increasing product returns have become particularly challenging for the efficient management of inventory. As such, at the crux of a holistic inventory model lies the understanding of consumer return behavior. In this study, we introduce a variant of the classical single-period inventory (newsvendor) model with returns, in which heterogeneous consumers decide, based on their post-purchase valuation of the product, whether to return the product after using it. From the perspective of the retailer, such deliberate returns may abuse the return policy, which in turn may exacerbate reverse logistics and environmental costs. To that end, we incorporate demand uncertainty and consumer valuation uncertainty by explicitly gauging return probabilities and differentiated salvage values into a newsvendor model. We derive analytical results for the profit-maximizing order quantity for a single-period product that comes with a retailer return policy and exclusively identify the impact of return type as abused or normal. Also offered are closed-form optimal solutions in the cases where market demand is exponentially or uniformly distributed. Structural and numerical results lend managerial insight into how optimal ordering amount, profit, return rates and salvage values change with the price, return window, and hassle cost of returning the product.
keywords: Inventory management |Consumer behavior |Product returns |Fraudulent proclivity |Uncertain demand |Return policy
Operational safety: The hidden cost of supply-demand mismatch in fashion and textiles related manufacturers
ایمنی عملیاتی: هزینه مخفی عدم هماهنگی عرضخه - تقاضا در سازنده های مربوط به مد و منسوجات-2018
Inventory management is a focus for operations management scholars and operations managers. Previous literature mainly investigated the relations between firms inventory and financial performance. However, the relation between firms inventory and non-financial performance (e.g., social outcome) is less clear. This study takes a fresh perspective to examine the impacts of supply-demand mismatch on firms safety performance. Based on a sample set from fashion and textiles related manufacturers, the analysis suggests that supply-demand mismatch (measured by inventory volatility) associates with a higher likelihood of safety incidents. The impact is more salient where the firms are operating in complex (labour intensive) and tightly coupled (high production capacity utilization) environments. This study provides significant contributions to the inventory management literature, occupational health and safety management literature and operational managers.
keywords: Inventory management |Occupational health and safety |Empirical study |Fashion and textiles
A supply chain coordination mechanism for common items subject to failure in the electronics, defense, and medical industries
یک مکانیزم هماهنگی زنجیره تامین برای کالاهای رایج درمعرض خرابی در صنایع برق، دفاعی و پزشکی-2018
Prior research on inventory management for imperfect items assumes that such items can be dealt with through salvage or rework. Increased repair costs and decreased production costs arising from modern production processes (e.g. miniaturization, 3D printing), however, have led suppliers to increasingly eschew such solutions in favor of items and components which are discarded upon failure rather than being reworked or scrapped. In this paper, we first determine optimal supplier and buyer inventory policies for items which fail and which cannot be reworked. We then develop a supply chain coordination mechanism which uses a common replenishment time to coordinate a supply chain consisting of a single supplier and n buyers. Our coordination mechanism yields a global minimum for system-wide costs. Numerical examples are provided to illustrate important conditions under which our model is particularly effective at reducing system-wide costs.
keywords: Inventory |Supply chain coordination |Supply chain management
Inventory component volatility and its relation to returns
فراریت مولفه انبارداری و رابطه آن با بازگشت ها-2018
Members of manufacturing supply chains have to take many risks. Prior academic work emphasizes that inventory management is one of the pivotal sources for operational risks, particularly in terms of inventory volatility and excess inventory. Recent research shows that total inventory volatility not only poses a threat to a firms operational performance, but also increases a firms abnormal stock returns. However, the volatility impact of the three underlying inventory components—raw materials, work-in-process, and finished goods—is still unresolved. We argue that the relationship between inventory volatility and stock returns differs between the three inventory components since they each relate to different stages of the supply chain. Using a sample of U.S. manufacturing firms over the period 2005 to 2013, we empirically examine the relationship between inventory component volatility and stock returns. We find a significant positive association between work-in-process inventory volatility and stock returns, a significant negative association between finished goods inventory volatility and stock returns, and no significant association between raw material inventory volatility and stock returns. In additional analyses, we find that types of industry dynamism influence these relationships. The results of this study provide a more detailed picture regarding the investor perception of inventory dynamics.
keywords: Operational risk |Inventory management |Stock returns |Raw material |Work-in-process |Finished goods