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Featured researches published by Salma Karray.


International Game Theory Review | 2007

EFFECTIVENESS OF COOP ADVERTISING PROGRAMS IN COMPETITIVE DISTRIBUTION CHANNELS

Salma Karray; Georges Zaccour

We propose a model of retail promotions for competitive distribution channels and investigate whether cooperative advertising programs are profitable for such channels. While previous studies showed that coop programs increase total channel profits in bilateral monopolies, no evidence of such a result has been provided for channels where competition is present at the manufacturing and the retailing levels. In this paper, we consider a distribution channel formed by two manufacturers and two retailers and propose a model that accounts for brand and store substitution effects generated by the retailers promotional efforts. The efficiency of the coop plan is investigated by comparing equilibria of four non-cooperative games; one where manufacturers do not offer any promotional support to the retailers, one where manufacturers do offer such a support and two scenarios where in turn only one manufacturer is offering such program. We show that when competition is introduced, coop ad programs may be due to a prisonners dilemma situation for the manufacturers. The benefit for retailers and consumers is also assessed.


European Journal of Operational Research | 2013

Periodicity of pricing and marketing efforts in a distribution channel

Salma Karray

Most research about cooperative (coop) advertising programs in channels relies on the assumption that manufacturers and retailers decide of pricing and marketing efforts simultaneously. This paper evaluates this central assumption and investigates the optimal periodicity (sequence of move) of pricing and marketing efforts (ME) decisions for a distribution channel. We develop a game theoretic model that accounts for pricing at each level of the channel, for the manufacturer’s ME mix strategies (a direct ME to consumers and coop advertising program offered to the retailer) and the retailer’s ME as well. We obtain solutions for a bilateral channel under different vertical interaction scenarios; when the channel is led by the manufacturer, the retailer or when channel members decide simultaneously of each of their marketing mix decisions (vertical Nash). We compare the effect of pricing and ME decision periodicity on outputs for each channel member. The main findings suggest that simultaneous decision-making of pricing and ME is optimal only for high enough levels of the manufacturer’s ME effects. For very highly effective marketing efforts, sequential play of pricing and ME allows channel members to implement equilibrium strategies and achieve maximum profits that would not be achieved with simultaneous decision-making. This highlights the importance of relaxing the simultaneous play assumption of pricing and ME in a distribution channel.


International Journal of Production Research | 2015

Cooperative advertising in a supply chain with retail competition

Salma Karray; Saman Hassanzadeh Amin

This research assesses the effects of cooperative (coop) advertising in a channel with competing retailers considering both advertising and pricing as decision variables. We develop a game-theoretic model and provide equilibrium solutions for two games. In Game 1, the manufacturer and the retailers do not use cooperative advertising (status quo); and in Game 2, coop advertising is implemented. We also obtain optimal solutions for the case where the channel is coordinated. Contrary to the results provided for one-manufacturer, one-retailer channels, we find that coop advertising may not be profitable for the retailers or for the channel, especially when the market is characterised by low levels of price competition and high advertising competition between retailers. Although it benefits the manufacturer, the total effect of cooperative advertising on the channel profit might be negative under such conditions. The results also show that coop advertising stimulates retailers’ spending but may result in lower advertising expenditures than for a fully coordinated channel. Finally, when coop advertising benefits the entire channel, it does not fully achieve results from vertical integration.


International Journal of Production Research | 2016

Channel coordination with quantity discounts and/or cooperative advertising

Salma Karray; Chirag Surti

We assess the interactive effects of two commonly used channel coordination mechanisms (quantity discounts (QDs) and cooperative advertising (CA)). We use a game-theoretic model and solve four non-cooperative games. In the first game, neither QDs nor CA is implemented. Cooperative advertising alone is offered in the second game, while quantity discounts alone are offered in the third game. In the fourth game, both QDs and CA are implemented. We obtain analytical solutions and compare equilibrium results across games to assess the effectiveness of CA (QDs) when implemented alone or jointly with QDs (CA). The main findings suggest that the profitability of each of these mechanisms is affected by whether the other is implemented or not in the channel. For example, while CA benefits the manufacturer when implemented alone, it can increase or decrease the manufacturer’s profit when added to QDs. Looking at which coordination mechanism is most effective when used alone, we find that both the manufacturer and the supply chain prefer QDs to CA. Finally, the retailer may not benefit from either one or both of these coordination mechanisms, especially if marketing efforts are not highly effective.


European Journal of Operational Research | 2016

Should companies jointly promote their complementary products when they compete in other product categories

Salma Karray; Simon Pierre Sigué

Joint promotions, whereby companies pool marketing resources to promote their brands, are increasingly used to reduce marketing costs and develop common business opportunities, but formal knowledge about how they should be effectively implemented remains sparse. This paper investigates whether firms should jointly promote their complementary products when they also offer substitute products in another category. It also studies whether companies should partner with allies that can or cannot leverage on joint promotion to create spillover in their product portfolios. Our main findings are as follows. A company’s decision to enter or not to enter into a joint promotion depends on the presence and nature (positive or negative) of promotion spillover in its own product portfolio and the effect of joint promotion on each complementary product demand. Particularly, in the absence of spillover effect, joint promotion may not be mutually beneficial if its direct effects on the two complementary products are asymmetric. On the other hand, depending on its direct effects on the complementary products, joint promotion could be a profit-enhancing activity for the two firms even when it negatively affects the demand of their substitute products by intensifying price competition. Finally, we discuss the implications of branding strategies on the effectiveness of joint promotion. The results in this paper are useful for firms offering products in different categories where joint promotional spillover can occur.


Annals of Operations Research | 2015

Modeling brand advertising with heterogeneous consumer response: channel implications

Salma Karray

The paper explores the implications of heterogeneous consumer response to advertising for the equilibrium strategies chosen by firms in a distribution channel. We solve a simple game theoretic model using a variation of consumers’ Hotelling utility model for a decentralized and a coordinated channel. The key findings show that heterogeneity considerably affects the value of channel coordination. Overlooking heterogeneous responses to advertising can lead to either undercutting or overestimating channel coordination benefits. In particular, our results indicate that, in contrast to previous findings in the literature, channel coordination might result in higher consumer prices especially when the average response to brand advertising exceeds consumers’ marginal disutility cost.


European Journal of Operational Research | 2019

Vendor Management Inventory with consignment contracts and the benefits of cooperative advertising

Pietro De Giovanni; Salma Karray; Guiomar Martín-Herrán

Abstract Most of the cooperative advertising literature has focused on studying the effects of such programs considering marketing variables. This paper integrates production and inventory management with pricing and advertising considerations to assess the effects of cooperative advertising programs in bilateral monopolies. We consider a supply chain where a Vendor Managed Inventory (VMI) along with a consignment contract is implemented to coordinate the chain. We develop and solve a differential model for two games. The first one is a benchmark scenario where no cooperative advertising is offered, while the manufacturer offers the cooperative program in the second game. The main results show that cooperative advertising programs, usually considered as successful marketing initiatives, can be very difficult to implement in a supply chain undertaking a VMI policy with a consignment contract, in which operations and marketing interface is taken into account. A cooperative program mainly hurts the manufacturer’s profits, and can be profit-Pareto-improving only in a few cases. Although the retailer is generally willing to receive a support from the manufacturer, she can opt for a non-cooperative program when the largest part of the supply chain profits goes to the manufacturer. We developed several special cases to strengthen our findings.


International Journal of Production Research | 2018

Joint advertising of complementary products sold through an independent retailer

Salma Karray; Simon Pierre Sigué

Two game-theoretic models are developed to study the profitability of joint advertising in a context where two manufacturers sell complementary products through an independent retailer and can either advertise separately or jointly. We find that it may not be in the interest of symmetric manufacturers to partner for advertising, especially when joint advertising is less effective than firms’ individual advertising and the degree of advertising complementarity between the two products is high. Conversely, the manufacturers prefer joint advertising to individual advertising programs even if its effectiveness is lower, but both the degrees of price and advertising complementarity are very large. Under these conditions, joint advertising is implemented at the expense of the retailer who suffers from the associated reduced demand for the two products. In such a context, the manufacturers’ advertising partnership mainly reduces advertising costs by mitigating double marginalisation in pricing. The extension to asymmetric manufacturers shows that the weaker manufacturer and the retailer can induce the stronger manufacturer to engage in joint advertising.


European Journal of Operational Research | 2018

‘Buy n times, get one free’ loyalty cards: Are they profitable for competing firms? A game theoretic analysis

Amirhossein Bazargan; Salma Karray; Saeed Zolfaghari

This paper evaluates whether firms offering loyalty programs (LPs) should choose a restricted redemption policy by imposing a specific number of purchases before customers can redeem their points. Such restriction is commonly offered in form of ‘buy n times, get one free’ loyalty cards. We develop a multinomial logit model where consumers utility depends on the value of the product and of the rewards. Using an iterative algorithm, we numerically solve a Nash game for two firms offering loyalty programs. Optimal strategies and profits are obtained for three different scenarios (games): (1) both firms do not restrict redemption; (2) both firms restrict redemption; and (3) only one firm restricts redemption while the other firm does not. Our main findings indicate that each firms optimal strategies are significantly affected by whether the competitor decides to restrict or not to restrict redemption. In particular, a firm that restricts reward redemption should offer a higher price if its competitor also restricts redemption. Further, the dominant strategy of the game depends on customers’ valuations of time and rewards. For example, when customers highly value time but do not highly value rewards, the dominant strategy for both firms is not to restrict redemption. Alternatively, firms can face a Prisoner dilemma situation leading to unrestricted redemption policy for intermediate levels of customer valuation of both time and rewards.


Electronic Commerce Research and Applications | 2018

Informational and/or Transactional Websites: Strategic Choices in a Distribution Channel

Salma Karray; Simon Pierre Sigué

Abstract While most businesses have faced the decision of whether to operate an informational and/or a transactional website, the literature on website selection in marketing channels remains very sparse. This paper proposes an analytical framework that compares scenarios where a manufacturer uses either an informational, a transactional, or both transactional and informational website in a distribution channel formed by one manufacturer and one retailer. We find that the selection of the optimal website depends on the online market base of the product, the effectiveness of the manufacturer-controlled online communications, and the cross-price effect between online and offline channels. For both the manufacturer and retailer, informational websites are preferable when the online market base is small. With larger online markets, the manufacturer may prefer either informational and transactional websites or exclusively informational websites, while the retailer is always better off with an exclusively informational website. Theoretical and managerial implications of these findings are discussed.

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Chirag Surti

University of Ontario Institute of Technology

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