The bullwhip effect is the phenomenon of increasing demand variability in the supply chain from downstream echelons (retail) to upstream echelons (manufacturing). The objective of this study is to document the strength of the bullwhip effect in industry-level U.S. data. In particular, we say an industry exhibits the bullwhip effect if the variance of the inflow of material to the industry (what macroeconomists often refer to as the variance of an industry's "production") is greater than the variance of the industry's sales. We find that wholesale industries exhibit a bullwhip effect, but retail industries generally do not exhibit the effect, nor do most manufacturing industries. Furthermore, we observe that manufacturing industries do not have substantially greater demand volatility than retail industries. Based on theoretical explanations for observing or not observing demand amplification, we are able to explain a substantial portion of the heterogeneity in the degree to which industries exhibit the bullwhip effect. In particular, the less seasonal an industry's demand, the more likely the industry amplifies volatility--highly seasonal industries tend to smooth demand volatility whereas nonseasonal industries tend to amplify.bullwhip effect, production smoothing, supply chain management, volatility

A disruptive innovation (i.e., one that dramatically disrupts the current market) is not necessarily a disruptive innovation (as Clayton Christensen defines this term). To aid in understanding why some innovations are more (or less) disruptive to the long‐term health of incumbents, this article offers terminology and a framework complementary to Christensen's work, focusing on the diffusion pattern of the new product. The framework and model presented herein suggest that when an innovation diffuses from the low end upward toward the high end, a pattern called low‐end encroachment, the incumbent may be tempted to overlook its potential impact. Three possible types of low‐end encroachment are illustrated: the fringe‐market, detached‐market, and immediate scenarios. Conversely, when the pattern is one of high‐end encroachment, the impact on the current market is immediate and striking. A three‐step framework is identified to assess the potential diffusion pattern and impact of an innovation, thereby helping a firm determine the threat or opportunity that an innovation represents.

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Past research (along with our experience) suggests that a firm's supply chain (i.e., value chain) plays an integral role in its ability to not only reduce cost via process innovation, but also in its ability to develop new products and services. Evidence suggests the value chain is playing an ever‐more‐important role, with greater prevalence of distributed product development (spanning geographic, organizational, or firm boundaries) and open innovation (performed outside the firm). We discuss some of the trends with regard to supplier and customer involvement in the innovation process, and summarize some of the research exploring the rationale behind those trends and the research offering advice on how firms can use external resources to further improve their innovation performance. We present a number of examples that illustrate some best practices.

Suppose you are a Marketing Manager envisioning a new product, or an Operations Manager contemplating a process improvement, or a CEO who commissioned an integrated new product development team. If our assumptions hold, our model offers you a single numerical measure, called the degree of product/process innovation, to determine your initiative's impact on potential sales, prices, market segments, and profits. Our simple, single-period model is a variation of the existing vertically differentiated products model: There are two competing substitute products, and customers will buy at most one of them. Our contribution is to allow new relationships between the valuations of the two products by potential customers, and to allow differing unit production costs. We identify equilibrium results when two competing firms each offer one product, and find the profit maximizing result when one (monopolistic) firm offers both products. The new product infringes on the market in one of two ways: High-end encroachment results when the new product attracts the best customers (those with the highest reservation prices), while low-end encroachment identifies a situation where the new product attracts fringe (lower-end) customers. Low-end encroachment may help explain why an incumbent sometimes fails to recognize the threat of an entrant's product, as we illustrate with an example from the disk drive industry. In short, we offer insight into the value of both a marketing objective (enhancing the product design attributes) and a manufacturing goal (lowering the production cost) in a product and/or process improvement project.degree of product/process innovation, low-end encroachment, high-end encroachment, reservation price, disruptive technology, operations strategy, vertically differentiated products

Diffusion theory has typically focused on how communication, internal or external to a social system, leads to adoptions and diffusion of an innovation. We develop a diffusion and substitution model based on a somewhat different perspective. In some cases, progressive improvements in product attributes and/or continual cost reduction seem to be a key driver of the diffusion process. For example, after introduction of the 5.25‐inch disk drive, its capacity continually increased, and accordingly, so did customer willingness‐to‐pay. Our model is based on a linear reservation price framework, in which a product is described by its depth (defined as the difference between a product̂s maximum reservation price and its production cost), and its breadth (related to the slope of its reservation price curve), indicating how broadly it appeals across various customer segments. Because of changes in product depths and breadths over time, customers who previously preferred the old product may later prefer the new product, thus creating the diffusion process. While the Bass model describes diffusion as a function of the coefficients of innovation and imitation, in our model, it is described by the coefficients of depth and breadth (the rates of change in relative depth and breadth), along with an S‐coefficient that we associate with the technology S‐curve. We fit our model to data from the disk‐drive and the microprocessor industries.

We build on the frameworks of Schmidt and Porteus (2000) and Schmidt and Druehl (2005), which describe alternate ways in which a new product might open a new market and ultimately encroach on an existing market. In the current paper we identify and analyze the scenario where a firm first opens up what we call a "detached" market, by offering a new product that meets a customer need that is very different from (i.e., detached from) the need met by the old established product. For example, cell phones opened up a new market by meeting the customer need for mobility; a need very different from the traditional attribute of reception quality. By meeting an important detached need, a new product can sell at a high price, even though it might be woefully deficient with regard to the traditional performance dimension (the reception / coverage of early cell phones was sorely lacking). A person who is a high-end customer for the old product initially despises the new product as a replacement for the old one, but might simultaneously be one of the first customers for the new product because it fills the detached-market need. Over time, the new product improves along the traditional dimension (e.g., cell-phone reception / coverage has dramatically improved) and eventually it becomes a replacement for the old product, but encroaches from the lower end upward (the first customers to drop their land lines have been lower-end customers such as students and apartment dwellers, while higher-end business customers still have land lines in their offices). We call this the detached-market form of low-end encroachment, and show how it helps explain the conundrum of an expensive "disruptive" innovation. We go on to relate our results to the finding that "willingness to cannibalize" is a key factor in an incumbent firm's growth and survival, and to the "blue ocean strategy."

A lthough product modularity is often advocated as a design strategy in the operations management literature, little is known about how consumers respond to modular products. In this research we undertake several experiments to explore consumer response to modularly upgradeable products in settings featuring technological change. We consider both the initial product choice (between a modularly upgradeable product and an integral one) and the subsequent upgrade decision (replacement of a module versus full product replacement). First, we show that consumers tend to discount the cost savings associated with modular upgrades excessively (insufficiently) when the time between the initial purchase and the upgrade is short (long). This suggests that modular upgradability as a product feature has higher profit potential for slowly rather than rapidly improving products. Second, we observe a preference reversal between the initial purchase and the point of upgrade: At the point of initial purchase, people foresee making a full product replacement in the future, yet, when faced with the actual upgrade decision, they are more likely to revert to modular upgrades. Finally, we discuss and test several pricing and product design strategies that the firm can use to respond to these cognitive biases.