buyer search costs and endogenous product design buyer search costs for price are changing in many markets through a model of buyer and seller behavior i consider the effects of changing search costs on prices both when product differentiation is fixed and when it is endogenously determined in equilibrium if firms cannot change product design lower buyer search costs for price lead to increased price competition however if product design is a decision variable lower search costs for price may also lead to higher product differentiation which decreases price competition in this case the overall effect of lower buyer search costs for price may even be higher prices lower social welfare and higher industry profits the result is especially interesting because recent technological changes such as internet shopping can affect the market structure through lowering buyer search costs

do switching costs make markets less competitive abstract the conventional wisdom in economic theory holds that switching costs make markets less competitive this article challenges this claim the authors formulate an empirically realistic model of dynamic price competition that allows for differentiated products and imperfect lock in they calibrate this model with data from frequently purchased packaged goods markets these data are ideal in the sense that they have the necessary variation to identify switching costs separately from consumer heterogeneity equally important consumers exhibit inertia in their brand choices a form of psychological switching cost this makes the results applicable to the broad range of products that are distinctly identified i e branded rather than just to products for which there is a product adoption cost or explicit switching fee in the simulations prices are as much as 18 lower with than without switching costs more important equilibrium prices do not increase even in the presence of switching costs that

durable goods monopolists durable goods monopolists face special problems because the sale of their products creates a secondhand market not controlled by the monopolist to the extent the monopolist is able to rent his product rather than sell it or to make binding promises about his future production such problems are ameliorated given the inability to do the above the monopolist is led to producing goods less durable than those produced by either competitive firms or monopolist returns a reverse averch johnson result that monopolist sellers may invest less in fixed costs including plant modernization and research and development than would the renters is shown it is also shown that even though sellers have less monopoly power than renters and nondurable goods monopolists it is possible that the seller will cause a greater deadweight loss than the other types of monopolies

the role of patent rights in mergers consolidation in plant biotechnology few micro level empirical papers have addressed the impact of the patent system on industry structure using firm level patent data for public and private firms in plant biotechnology we develop a measure of patent enforceability duration models show that patent statistics are a useful predictor of the timing of merger activity we find that patent enforceability is an important factor influencing the likelihood of mergers mergers in plant biotechnology may be partially motivated by the enforcement of patent rights when firms have overlapping technologies some of the merger activity may be explained by attempts to avoid mutually blocking technology as exemplified in the case of roundup ready corn

potential pitfalls for the purchasing power parity puzzle sampling and specification biases in mean reversion tests of the law of one price the ppp puzzle is based on empirical evidence that international price differences for individual goods loop or baskets of goods ppp appear highly persistent or even nonstationary the present consensus is these price differences have a half life that is of the order of five years at best and infinity at worst this seems unreasonable in a world where transportation and transaction costs appear so low as to encourage arbitrage and the convergence of price gaps over much shorter horizons typically days or weeks however current empirics rely on a particular choice of methodology involving i relatively low frequency monthly quarterly or annual data and ii a linear model specification in fact these methodological choices are not innocent and they can be shown to bias analysis towards findings of slow convergence and a random walk intuitively if we suspect that the actual adjustment horizon is of the order of days then monthly and annual data cannot be expected to reveal it if we suspect arbitrage costs are high enough to produce a substantial band of inaction then a linear model will fail to support convergence if the process spends considerable time random walking in that band thus when testing for ppp or loop model specification and data sampling should not proceed without consideration of the actual institutional context and logistical framework of markets

durable goods oligopoly abstract this paper models a durable goods oligopoly as a differential game two cases are treated sales where firms cannot lease but must sell the good in question and leasing where firms do not sell but only rent in the sales case firms face increasing marginal cost of production and the good in question depreciates for this case a rational expectations feedback nash equilibrium is constructed for which monopoly or oligopoly output is less than the efficient level this gap between oligopoly and competitive output diminishes as the number of firms increases when firms can only lease the good the good is assumed not to depreciate and the monopoly level of steady state output is compared with the level of steady state output for a feedback equilibrium duopoly for this case the duopoly equilibrium has steady state output that is less than the corresponding efficient level but greater than the monopoly level the leasing model is shown to be isomorphic to the adjustment cost duopoly model of driskill and mccafferty journal of economic theory 49 1989 324 338

reward programs and tacit collusion reward programs a promotional tool to develop customer loyalty offer incentives to consumers on the basis of cumulative purchases of a given product or service from a firm reward programs have become increasingly common in many industries the best known examples include frequent flier programs offered by airlines frequent guest programs offered by hotels and frequent shopper programs offered by supermarkets despite the widespread business practice of reward programs research efforts on reward programs particularly in marketing have been scarce our paper takes an important step towards understanding the design of reward programs and its implications on pricing strategies we study a market that consists of two segments heavy and light user segments the key distinction between the two segments is that the heavy user segment purchases in each period and thus is a candidate for the reward programs in contrast the light user segment exits the market after one purchase and is not in a position to exploit reward programs an important feature of our model is that we allow for different price sensitivity between heavy user and light user segments our model closely examines the type of rewards a reward worth a dollar to the consumer might have different cost implications for the offering firm depending on the type of reward for example cash rewards have higher unit reward cost inefficient reward for the firm than a free product of the firm such as an airline ticket or long distance minutes efficient reward specifically we examine an interesting puzzle observed in the marketplace several firms offer a cash reward or a product not made by the firm such as jackets electronic items etc these firms could offer their own product as rewards and significantly lower their cost we examine whether there is any reason for such a seemingly suboptimal practice our analysis shows that reward programs weaken price competition by offering the incentives for repeat purchases reward programs increase a firm s cost to attract competing firms current customers because firms gain less from undercutting their prices equilibrium prices go up moreover as consumers become unwilling to switch because of potential rewards the firm with a larger market share in the heavy user segment charges higher prices therefore a low price in the first period which leads to a larger market share in the heavy user segment will always be followed by a high price in the second period in our model consumers are rational and can correctly anticipate firms incentive to offer lower prices initially to enroll them into the reward programs our paper offers an explanation as to why the type and amount of reward may vary across the programs we identify two determining factors for the selection of rewards size and relative price sensitivity of the heavy user segment we find that in a market with a small heavy user segment that is also much more price sensitive than the light user segment it is optimal for firms to offer the most inefficient rewards the intuition is based on the firms incentive to exploit the price insensitive light user segment by offering inefficient rewards firms are able to commit to weaker competition and therefore higher prices when the heavy user segment is large or not very price sensitive when compared to the light user segment competing firms should adopt the most efficient rewards to maximize their profit this may well be the case in a number of real world situations in which efficient rewards are quite prevalent we also find that optimal reward amount has a negative relationship with unit reward cost because both firms use rewards to attract the heavy users they tend to offer more when they adopt the more efficient rewards finally our paper identifies the relationship between market characteristics and theimpact of reward programs on firms profits and consumers benefits we find that firms gain from the adoption of reward programs as long as light users are not too price sensitive when light users are very price sensitive firms engage in intense price competition thus benefiting little from the loyalty of heavy users created through rewards because reward programs increase market prices light users who do not get the reward earn strictly lower benefit in contrast heavy users often stand to gain more from the reward program in most cases firms and the heavy users are better off at the expense of light users

price discrimination in free entry markets using a spatial model of monopolistic competition we investigate price discrimination in free entry zero profit markets we show that when brands are heterogeneous competition does not prevent discrimination the power to earn economic profits is not necessary for a firm to maintain discriminatory prices our model treats formally the fact that consumers difer not only in the utility they derive from a good but also in how strongly they prefer one brand over all others in markets where firms are very competitive sorting consumers on the strength on brand preference produces larger price differentials between groups than sorting on the basis of consumers reservation prices for the good when firms sort customers on the basis of strength of brand preference however we find that the output and welfare effects are generally less favorable than when sorting is more closely related to consumers reservation prices

tax incidence in differentiated product oligopoly abstract we analyze the incidence of ad valorem and unit excise taxes in an oligopolistic industry with differentiated products and price setting bertrand firms both taxes may be passed on to consumers by more than 100 percent and an increase in the tax rate can increase short run firm profits and hence the long run number of firms we provide summary conditions for these effects to arise the conditions depend on demand curvatures and are written in elasticity form surprisingly the analysis largely corroborates cournot results with homogeneous demand

the economic impact of wireless number portability this paper examines the price response of wireless carriers to the introduction of number portability in the u s i find that wireless prices decreased in response to number portability but not uniformly across plans average prices for the plans with the fewest minutes decreased by only 0 19 month 0 97 but average prices for medium and high volume plans decreased by 3 64 month 4 84 and 10 29 month 6 81 respectively the results suggest that higher volume users in the wireless market benefited more from the policy induced reduction in switching costs

digital piracy a competitive analysis in recent years the issue of copyright protection for intellectual properties such as computer software music cds and videos has become increasingly important it is often claimed that illegal copying of intellectual property costs companies billions of dollars in lost revenues and reduces firms incentives to innovate some researchers have shown that copying can be beneficial to firms when there are strong network effects and copying expands the market in this paper we first examine the impact of illegal copying of software and other similar intellectual properties on firms prices profits and quality choices even when there are no network effects and the market is saturated we show that contrary to the claims of manufacturers there are conditions under which copying can increase firms profits lead to better quality products and increase social welfare this is because weaker copyright protection enables firms to reduce price competition by allowing price sensitive consumers to copy thus weaker copyright protection can serve as a coordination device to reduce price competition we also examine how equilibrium copyright enforcement is affected by network externalities in contrast to previous research we show that strong network effects can sometimes lead to a firm choosing higher levels of copyright protection our results show that in the presence of strong network effects stronger copyright enforcement by one firm can serve as a coordinating device to reduce price competition

further evidence regarding nonlinear trend reversion of real gdp and the cpi abstract this paper examines whether the cpi and real gdp for the us exhibit nonlinear reversion to trend as recently concluded by beechey and osterholm beechey m and osterholm p 2008 revisiting the uncertain unit root in gdp and cpi testing for nonlinear trend reversion economics letters 100 221 223 the wild bootstrap is used to correct for non normality and heteroscedasticity in a nonlinear unit root test the use of wild bootstrapped critical values affects test conclusions in some cases results also are sensitive to the sample period examined

competitive price discrimination we model firms as supplying utility directly to consumers the equilibrium outcome of competition in utility space depends on the relationship u between profit and average utility per consumer public policy constraints on the deals firms may offer affect equilibrium outcomes via their effect on u f rom this perspective we examine the profit utility and welfare implications of price discrimination policies in an oligopolistic framework we also show that an equilibrium outcome of competitive nonlinear pricing when consumers have private information about their tastes is for firms to offer efficient two part tariffs

competition in durable goods markets the strategic consequences of leasing and selling in marketing durable goods manufacturers use varying degrees of leasing and selling to consumers e g cars photo copiers personal computers airplanes etc the question that this raises is whether the distinction between leases and sales is simply one of price or whether the proportion of leases and sales effects a firm s ability to compete in the market in this paper we use two approaches to argue that leasing and selling create strategic consequences that extend beyond prices first we develop a stylized theoretical model that shows that the optimal proportion of leases and sales depends on the competitiveness of the market and on the inherent reliability of the firm s product and second we find support for the implications of our theoretical model with data from the automobile industry the u s automobile industry has seen a large increase in leasing over the last five years however the extent to which leasing has been embraced varies widely across manufacturers for example in 1993 the sport utility segment had the following lease percentages ford explorer 29 jeep grand cherokee 24 toyota 4 runner 11 and chevrolet blazer 9 in addition manufacturers often vary lease percentages across models for example in 1993 ford leased 22 of its crown victoria model 35 of its taurus model and 42 of its probe model a popular argument for why we see these differences is that higher priced cars are leased more often because leasing makes them more affordable however this rationale is not compelling in the face of our data for example the ford probe was priced significantly lower than the crown victoria and yet it was leased almost twice as often to develop a better understanding of why we observe differences in the proportion of leasing we develop a two period model of a duopoly in which each manufacturer chooses its optimal quantity and the fraction of units it wants to lease we find that in equilibrium neither firm leases all its units either they use a mix of leasing and selling or they use only selling our analysis suggests that the fraction of leased cars decreases as the manufacturers products become more similar and the competition between them increases the intuition for this result is that a higher fraction of leases puts the firm at a competitive disadvantage in the future this occurs because unlike firms that sell their product firms that lease are at a price disadvantage another important finding in this paper is that the extent of leasing chosen by a manufacturer depends on the reliability of its product in particular all else being equal the lower a product s reliability the lower its proportion of leases within the context of the automobile industry this suggests that more expensive cars may be leased more often because they are of higher quality and not necessarily because they are more expensive finally we test the implications of our theoretical model with data from the u s automobile market in particular for 1993 model year cars we develop a measure of reliability using data from consumer reports in addition we develop a measure of the extent of competition in each segment of the automobile market we support our hypotheses by finding that the extent to which a car model is leased depends strongly on its predicted reliability and on the competitive intensity within the segment

strategic decentralization in channels the purpose of this paper is to understand the effect of strategic interaction on a manufacturer s channel structure decision in the model i analyze if there were no strategic interaction then the manufacturer would prefer vertical integration to decentralization with strategic interaction however decentralization can be a nash equilibrium strategy as mcguire and staein mcguire timothy richard staelin 1983a an industry equilibrium analysis of downstream vertical integration marketing sci 2spring 161 192 showed so the question arises what is it about strategic interaction that makes decentralization a nash equilibrium strategy the answer i give is that strategic interaction makes it possible for a manufacturer s retail demand curve to rise when he decentralizes i show that this raising of the demand curve on decentralization can happen only if one of the following mutually exclusive conditions is satisfied 1 the manufacturers products are demand substitutes at the retail level and strategic complements at the manufacturer or retailer levels 2 the manufacturer s products are demand complements at the retail level and strategic substitutes at the manufacturer or retailer levels strategic complementarity at the retailer manufacturer level means that if one retailer manufacturer raises his price then the other retailer manufacturer would raise his price as well strategic substitutability is just the opposite these results show that what is important for decentralization to occur is not how demand substitutable the two manufacturers products are as one might have thought from earlier works in the literature but rather the nature of coupling between demand dependence and strategic dependence

the learning curve market dominance and predatory pricing sufficient conditions for id and iid are given in the case of two step learning in which a firm reaches the bottom of its learning curve after just two sales however examples are also constructed for the two step learning case in which neither id nor iid holds it is also shown that in equilibrium iid implies that learning is privately disadvantageous although it is socially advantageous finally introducing avoidable fixed costs and possible exit into the model yields a new theory of predatory pricing based on the learning curve hypothesis

intraconnectivity and interconnectivity when value creation may reduce profits this paper analyses firms decisions to provide connectivity to their customers we distinguish between intraconnectivity the ability of one firm s customers to connect to each other and interconnectivity the ability of one firm s customers to connect with another firm s customers the profitability implications of allowing connectivity are not a straightforward consequence of the consumer value of connectivity because connectivity affects not only the customer value but also the intensity of competition by creating or changing network externality we find that if sales are driven by brand switching rather than by category expansion a firm may find it optimal not to provide intraconnectivity even if providing it is not costly and may find it optimal to provide interconnectivity even at a cost exceeding the consumer value of connectivity on the other hand if category expansion is possible providing intraconnectivity may be profitable in this case either the equilibrium intraconnectivity provision may be asymmetric or both firms may find it individually optimal to provide intraconnectivity under certain conditions in the latter case the firms choice of intraconnectivity is a prisoner s dilemma game

games with strategic complementarities new applications to industrial organization this paper provides an introduction to the analysis of games with strategic complementarities and applications to industrial organization oligopoly pricing comparative statics and a taxonomy of strategic behavior in two stage games

bertrand supertraps we study oligopoly price competition between multiproduct firms firms whose products interact in the profit function specifically we focus on the impact of intrafirm product interactions on the level of equilibrium profits this impact may be decomposed in two different ways a a direct effect keeping the competitors actions fixed plus a strategic effect i e through the competitors actions or alternatively b a competitive advantage effect change in firmi only plus an imitation effect change in all other firms we derive conditions such that a the strategic effect more than outweighs the direct effect and conditions such that b the imitation effect more than outweighs the competitive advantage effect bertrand supertraps for example an increase in the degree of economies of scope would increase profits if prices were fixed or if the change were limited to firmi s cost function however if all firms increase the degree of economies of scope then all firms receive lower profits a variety of other applications is considered including learning curves core competencies demand synergies systems competition compatibility bundling network effects switching costs durable goods long term contracts

collusion in bertrand vs cournot competition a virtual bargaining approach how do firms manage to collude without communicating why do we find more collusion in price competition than in quantity competition why is collusion so hard to detect we examine strategic behavior in competitive interactions by developing and applying the concept of virtual bargaining when decision makers virtually bargain they mentally simulate and choose among agreements that they could reach if they were able to explicitly negotiate with each other virtual bargainers focus on agreements that offer some protection against the possibility that their counterparts may deviate and best respond to these agreements we develop a formal account of virtual bargaining and demonstrate that it leads to collusion in bertrand but not in cournot competition in this framework collusion is a result of virtual bargaining as a mode of reasoning and requires neither communication nor dynamic considerations such as rewards and punishments between the players this paper was accepted by manel baucells decisi

why market shares matter an information based theory consider a duopoly market in which consumers have heterogeneous information about the quality differential q of the two goods when firms are ignorant about q consumers rationally believe that a firm with high market shares is likely to produce a high quality good as a result firms try to signal jam the inferences of consumers and compete for market shares beyond the level explained by short run profit maximization when firms know q multiple equilibria may exist but there is always one equilibrium in which market shares signal quality and then the market tends to be more competitive

we re number 1 price wars for market share leadership i examine the dynamics of oligopolies when firms derive subjective value from market leadership in equilibrium prices alternate in tandem between high levels and occasional price wars which take place when market leadership is at stake the stationary distribution of market shares is typically multimodal that is much of the time there is a stable market leader even though shareholders do not value market leadership per se a corporate culture that values market leadership may increase shareholder value the online appendix is available at https doi org 10 1287 mnsc 2017 2725 this paper was accepted by bruno cassiman business strategy

technology adoption in the presence of network externalities we analyze technology adoption in industries where network externalities are significant the pattern of adoption depends on whether technologies are sponsored a sponsor is an entity that has property rights to the technology and hence is willing to make investments to promote it key findings include the following 1 compatibility tends to be undersupplied by the market but excessive standardization can occur 2 in the absence of sponsors the technology superior today has a strategic advantage and is likely to dominate the market 3 when one of two rival technologies is sponsored that technology has a strategic advantage and may be adopted even if it is inferior 4 when two competing technologies both are sponsored the technology that will be superior tomorrow has a strategic advantage

cross market network effect with asymmetric customer loyalty implications for competitive advantage a cross market network effect exists in many industries e g newspaper publishing media software in which a seller sells both a primary and a secondary product e g a newspaper publisher sells newspapers to readers and advertising space to advertisers and the value of the secondary product depends on the size of the user base of the primary product this paper examines the competitive implications of asymmetric customer loyalty in such markets in traditional markets an advantage in customer loyalty generates a profit advantage we show here however that in the presence of a cross market network effect a midlevel of loyalty advantage in the primary product market can lead to an overall profit disadvantage this surprising result is derived from the interdependence of the two markets whereby a profit in one market may be gained at the cost of the other and by the positive relationship between a larger loyalty segment and a higher opportunity cost of price competition in the product of the primary market extending our model to a two period entry game also shows that under certain conditions the entrant with disadvantage in customer loyalty can outperform the incumbent in profit and market share this result suggests that asymmetry in customer loyalty can be a source of first mover advantage or disadvantage

third degree price discrimination in oligopoly all out competition and strategic commitment price discrimination by imperfectly competitive firms may intensify competition leading to lower prices for all consumers the tradeoff of consumer groups welfare that is characteristic of monopolistic discrimination need not arise this escalation of competition may make firms worse off and as a result firms may wish to avoid the discriminatory outcome under conditions similar to those in which unambiguous price and welfare effects may arise unilateral commitments not to price discriminate including the adoption of everyday low pricing or no haggle policies may raise firm profits by softening price competition

one is almost enough for monopoly it has been argued that two factors product durability and potential entry may force a monopolist to price at marginal cost this article shows that when these two forces coexist the tendency toward competition may be negated first we prove that durable goods oligopolists without commitment powers may attain joint profits arbitrarily close to those of a monopolist with perfect commitment power second we demonstrate that the presence of a potential entrant may enable a durable goods monopolist to act as if he had commitment power thus potential as well as actual entry may restore monopoly power

non linearity versus non normality in real exchange rate dynamics we distinguish non normality from non linearity in g7 real exchange rate dynamics by correcting the critical values of the kapetanios et al kapetanios g shin y snell a 2003 testing for a unit root in the non linear star framework journal of econometrics 112 359 379 test for non normality using the wild bootstrap our findings validate non linear purchasing power parity net of non normality effects

dynamic price competition with network effects i consider a dynamic model of competition between two proprietary networks consumers die and are replaced with a constant hazard rate and firms compete for new consumers to join their network by offering network entry prices i derive a series of results pertaining to a existence and uniqueness of symmetric equilibria b monotonicity of the pricing function e g larger networks set higher prices c network size dynamics increasing dominance vs reversion to the mean and d firm value how it varies with network effects finally i apply my general framework to the study of termination charges in wireless telecommunications i consider various forms of regulation and examine their impact on firm profits and market share dynamics

why firms may prefer not to price discriminate via mixed bundling abstract we analyze a simple model of joint purchase discounts using a discrete choice framework to characterize consumer choices the model suggests that mixed bundling is more likely to be associated with monopoly this is due to the benefits reaped via price discrimination in a duopoly environment however only pure components pricing may be offered in equilibrium since firms fear the extra degree of competition inherent in mixed bundling

quality incentives for gps in a regulated market abstract this paper analyses whether gps in a capitation system have incentives to provide quality even though health is a credence good a model is developed where the quality of the service varies due to inherent differences between the gps and rational patients make choices based on the outcome of treamtent we find that it is difficult to provide appropriate incentives since the search activity of patients offsets direct effects of a change in reimbursement variation in the inherent ability of the gps is good since it increases the search activity of the patients and the optimal reimbursement scheme is inversely proportional to the dispersion in types finally we find that offering a menu of contracts can potentially increase social welfare above the level of a simple capitation regime but it tends to lead to a higher variation in quality levels

consumer learning brand loyalty and competition in several markets consumers can gain further information regarding how well a product fits their preferences only by experiencing it after purchase this could then generate loyalty for the products tried first this paper considers a model in which consumers learn in the first period about the product they buy and then make choices in the second period about the competing products given what they learned in the first period the paper finds that if the distribution of valuations for each product is negatively positively skewed a firm benefits is hurt in the future from having a greater market share today the brand loyalty characteristic with negative skewness two effects are identified on one hand marginal forward looking consumers are less price sensitive than myopic consumers and this is a force toward higher prices on the other hand forward looking firms realize that they gain in the future from having a higher market share in the current period and compete more aggressively in prices for similar discount factors for consumers and firms the latter effect dominates the paper also characterizes the importance of consumer learning effects on the market outcome

revisiting the uncertain unit root in gdp and cpi testing for non linear trend reversion we test for the presence of a unit root in u s gdp and cpi allowing for non linear trend reversion under the alternative hypothesis in contrast to most previous results we find evidence in favour of trend stationarity for both variables

sharing the wealth when should firms treat customers as partners marketers often stress the importance of treating customers as partners a fundamental premise of this perspective is that all parties can be weakly better off if they work together to increase joint surplus and reach pareto efficient agreements for marketing managers this implies organizing marketing activities in a manner that maximizes total surplus this logic is theoretically sound when agreements between partners are limitless and costless in most consumer marketing contexts business to consumer this is typically not true the question i ask is should one still expect firms to partner with consumers and reach pareto efficient agreements in this paper i use the example of a firm s choice of product configuration to demonstrate two effects first i show that a firm may configure a product in a manner that reduces total surplus but increases firm profits second one might conjecture that increased competition would eliminate this effect but i show that in a duopoly firm profits may be increasing in the cost of product completion this second result suggests that firms may prefer to remain inefficient and or stifie innovations both results violate a fundamental premise of partnering that firms and consumers should work together to increase total surplus and reach pareto efficient agreements the model illustrates that pareto efficient agreements are less likely to occur if negotiation with individual partners is infeasible or costly such as in business to consumer contexts consumer marketers in one to many marketing environments should be wary of treating customers as partners because pareto efficient agreements may not be optimal for their firm

rationalizability learning and equilibrium in games with strategic complementarities we study a rich class of noncooperative games that includes models of oligopoly competition macroeconomic coordination failures arms races bank runs technology adoption and diffusion r d competition pretrial bargaining coordination in teams and many others for all these games the sets of pure strategy nash equilibria correlated equilibria and rationalizable strategies have identical bounds also for a class of models of dynamic adaptive choice behavior that encompasses both best response dynamics and bayesian learning the players choices lie eventually within the same bounds these bounds are shown to vary monotonically with certain exogenous parameters we study the class of noncooperative supermodular games introduced by topkis 1979 and further analyzed by vives 1985 1989 who also pointed out the importance of these games in industrial economics supermodular games are games in which each player s strategy set is partially ordered the marginal returns to increasing one s strategy rise with increases in the competitors strategies so that the game exhibits strategic complementarity 2 and if a player s strategies are multidimensional marginal returns to any one com ponent of the player s strategy rise with increases in the other components this class turns out to encompass many of the most important economic applications of noncooperative game theory in macroeconomics diamond s 1982 search model and bryant s 1983 1984 rational expectations models can be represented as supermodular games in each of these models more activity by some members of the economy raises the returns to increased levels of activity by others in oligopoly theory some models of bertrand oligopoly with differentiated products qualify as supermodu lar games in these games when a firm s competitors raise their prices the marginal profitability of the firm s own price increase rises a similar structure is present in games of new technology adoption such as those of dybvig and spatt 1983 farrell and saloner 1986 and katz and shapiro 1986 when more users hook into a communication system or more manufacturers adopt an interface standard the marginal return to others of doing the same often rises similarly in some specifications of the bank runs model introduced by diamond and dybvig 1983 when more depositors withdraw their funds from a bank it is more worthwhile for other depositors to do the same in the warrant exercise

the strategic value of high cost customers many firms today manage their existing customers differentially based on profit potential providing fewer incentives to less profitable customers and firing unprofitable customers although researchers and industry experts advocate this practice results have been mixed we examine this practice explicitly accounting for competition and find that some conventional prescriptions may not always hold we analyze a setting where customers differ in their cost to serve we find that when a firm can discriminate among its customers but the rival cannot customer base composition influences the rival s poaching behavior consequently even though a low cost customer is more profitable when viewed in isolation a high cost customer may be strategically more valuable by discouraging poaching therefore contrary to conventional advice it can be profitable for a firm to retain unprofitable customers moreover some customers may become more valuable to retain and receive better incentives when they are less profitable we further show that in competitive settings traditional customer lifetime value metrics may lead to poor retention decisions because they do not account for the competitive externality that actions toward some customers impose on the cash flows from other customers our results suggest that firms may need to evolve from a segmentation mindset which views each customer in isolation to a customer portfolio mindset which recognizes that the value of different customers is interlinked this paper was accepted by j miguel villas boas marketing