T he ISO 9000 series of quality management systems standards, introduced in 1986, has been adopted at over 560,000 locations worldwide. Anecdotal evidence suggests that firms can achieve internal benefits such as quality or productivity improvements or that certification can help firms maintain or increase their market share, or both. Others argue that the standard is too generic to cause performance improvement but can be seen as a signal of good management. In this paper, we track financial performance from 1987 to 1997 of all publicly traded ISO 9000 certified manufacturing firms in the United States with SIC codes 2000-3999, and test whether ISO 9000 certification leads to productivity improvements, market benefits, and improved financial performance. We employ event-study methods, matching each certified firm to a control group of one or more noncertified firms in the same industry with similar precertification size and/or return on assets. We find that firms' decision to seek their first ISO 9000 certification was indeed followed by significant abnormal improvements in financial performance, though the exact timing and magnitude of this effect depend on the specification of the control group. Three years after certification, the certified firms do display strongly significant abnormal performance under all control-group specifications. The degree to which the precise results vary across control-group specifications indicates that event studies should always include extensive sensitivity analysis, for instance matching by size and performance separately and jointly, using both single firms and portfolios as controls.

The view that adopting an environmental perspective on operations can lead to improved operations is in itself not novel; phrases such as "lean is green" are increasingly commonplace. The implication is that any operational system that has minimized inefficiencies is also more environmentally sustainable. However, in this paper we argue that the underlying mechanism is one of extending the horizons of analysis and that this applies to both theory and practice of operations management. We illustrate this through two principal areas of lean operations, where we identify how successive extensions of the prevailing research horizon in each area have led to major advances in theory and practice. First, in quality management, the initial emphasis on statistical quality control of individual operations was extended through total quality management to include a broader process encompassing customer requirements and suppliers' operations. More recently, the environmental perspective extended the definition of customers to stakeholders and defects to any form of waste. Second, in supply chain management, the horizon first expanded from the initial focus on optimizing inventory control with a single planner to including multiple organizations with conflicting objectives and private information. The environmental perspective draws attention to aspects such as reverse flows and end-of-life product disposal, again potentially improving the performance of the overall supply chain. In both cases, these developments were initially driven by practice, where many of the benefits of adopting an environmental perspective were unexpected. Given that these unexpected side benefits seem to recur so frequently, we refer to this phenomenon as the "law of the expected unexpected side benefits." We conclude by extrapolating from the developmental paths of total quality management and supply chain management to speculate about the future of environmental research in operations management.environmental management, sustainability, quality management, supply chain management

The ISO 9000 series of quality management systems standards and the more recent ISO 14000 environmental management systems standards have generated much controversy among practitioners. Although ISO 9000 has become a de facto requirement for many firms, its effects are poorly understood, and similarly the value and domain of applicability of ISO 14000 have been questioned. This paper reports on an exploratory study into the global spread of ISO 14000. We interviewed practitioners worldwide to identify factors that they believe explain differences between national ISO 14000 certification counts. We then collected quantititive data for these factors and, using regression analysis, we found that exports, environmental attitudes (combined with economic development), and ISO 9000 certification count were significant. The fact that ISO 9000 appears as an important factor explaining diffusion of ISO 14000 certifications suggests that the drivers behind the two have significant overlap. This indicates that, although ISO 14000 is an environmental standard, many of the factors driving national certification patterns are not at all environmental in nature, and that ISO 14000 therefore needs to be studied from a broader perspective than from a purely environmental point of view. (ISO 9000; ISO 14000; ENVIRONMENTAL MANAGEMENT SYSTEMS; QUALITY MANAGE-MENT; INTERNATIONAL DIFFUSION) *

In the supply-chain literature, an increasing body of work studies how suppliers can use incentive schemes such as quantity discounts to influence buyers' ordering behaviour, thus reducing the supplier's (and the total supply chain's) costs. Various functional forms for such incentive schemes have been proposed, but a critical assumption always made is that the supplier has full information about the buyer's cost structure. We derive the optimal quantity discount policy under asymmetric information and compare it to the situation where the supplier has full information.supply contracts, coordination, lot sizing, quantity discounts, asymmetric information

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This paper studies the value to a supplier of obtaining better information about a buyer's cost structure, and of being able to offer more general contracts. We use the bilateral monopoly setting to analyze six scenarios: three increasingly general contracts (wholesale-pricing schemes, two-part linear schemes, and twopart nonlinear schemes), each under full and incomplete information about the buyer's cost structure. We allow both sides to refuse to trade by explicitly including reservation profit levels for both; for the supplier, this is implemented through a cutoff policy. We derive the supplier's optimal contracts and profits for all six scenarios and examine the value of information and of more general contracts. Our key findings are as follows: First, the value of information is higher under two-part contracts; second, the value of offering two-part contracts is higher under full information; and third, the proportion of buyers the supplier will choose to exclude can be substantial.supply chains, contracting, pricing, asymmetric information

Supply chains often consist of several tiers, with different numbers of firms competing at each tier. A major determinant of the structure of supply chains is the cost structure associated with the underlying manufacturing process. In this paper, we examine the impact of fixed and variable costs on the structure and competitiveness of supply chains with a serial structure and price-sensitive linear deterministic demand. The entry stage is modeled as a simultaneous game, where the players take the outcomes of the subsequent post-entry (Cournot) competition into account in making their entry decisions. We derive expressions for prices and production quantities as functions of the number of entrants at each tier of a multitier chain. We characterize viability and stability of supply-chain structures and show, using lattice arguments, that there is always an equilibrium structure in pure strategies in the entry game. Finally, we examine the effects of vertical integration in the two-tier case. Altogether, the paper provides a framework for comparing a variety of supply-chain structures and for studying how they are affected by cost structures and by the number of entrants throughout the chain.Supply Chains, Competition, Pricing, Production, Entry, Fixed Costs