市场竞争中具溢出效应共同供应商质量投资策略

Quality investment in a shared supplier with spillover effects in a competitive market

产品质量是一个重要竞争维度,制造商有动机对供应商进行质量投资来提高产品质量水平。但一个供应商有可能与多个制造商存在合作,导致制造商的质量投资产生溢出从而提高其竞争对手的产品质量水平。本文研究存在质量溢出效应的情况下制造商是否应对供应商进行质量投资的问题。考虑由一个供应商和两个竞争性制造商组成的供应链,分别构建了无质量投资、单一制造商进行质量投资和两个制造商进行质量投资三种情形下的决策模型,刻画了溢出系数对均衡结果的影响。研究表明:供应商更希望两个制造商在相对较弱的溢出效应下共同进行质量投资。对制造商而言,无论溢出效应如何或者竞争对手投资与否,一个制造商的最优策略是对供应商进行质量投资。

In this paper, we analyze the role of product quality, which is defined as a set of product attributes that increase consumers＇ willingness to buy, as acompetitive tool in a quality- and price-sensitive market. Nowadays, a growing number of manufacturers focus on product research and development （R＆D）,and marketing activities. These manufacturers outsource their product design and production to the upstream suppliers as a key alternative to gainingcompetitive advantages. As a result, manufacturers cannot directly control the levels of product quality. Meanwhile, the supplier plays a very important role inshaping the manufacturer＇s competitiveness. Therefore, when there are product quality improvement opportunities in the supplier, the manufacturer often hasincentives to help the supplier improve quality levels through quality investment. However, the supplier otten works with multiple manufacturers and thebenefit of quality investment may spill over to the competitors of the investor（s）. In this study, we explore how potential spillover effects may influence the manufacturers＇ incentives to invest in a shared supplier by developing gametheoretic models under three scenarios： no manufacturers invest in the supplier, a single manufacturer does, and both of them do. We obtain the manufacturers＇equilibrium retail prices, quality investment levels, and the supplier＇s wholesale prices. Then, we compare the optimal decisions, the supplier＇s profit, and themanufacturers＇ profit in the above three scenarios and find that： 1） The supplier charges the investor a higher wholesale price which is decreasing in the spillover factor. If the spillover factor is lower enough, he chargesthe free rider a smaller wholesale price which is increasing in the spillover factor. 2） Any manufacturer that invests in the shared supplier would raise the retail price, which, however, is decreasing in the spillover factor. Free riders adoptprice-increasing policy only when the spillover factor is strong enough. 3） The supplier is better off when there is quality investment. In addition, the more investors or the lower the spillover factor, the larger the supplier＇sadded profit. 4） Both the spillover factor and the number of investors have important effect on the two manufacturers＇ optimal profits. In particular： i） When onemanufacturer makes quality investment, the investor always gains more profit, but the free rider is better off if and only if the spillover factor is above athreshold. Moreover, the lower the spillover factor is, the more the free rider loses and the greater the investor gains, ii） Each of the manufacturers haveincentives to invest in the shared supplier. Under this case, both investors suffer a loss if the spillover factor is lower enough than what they could gain under thecase where there is no quality investment. However, free riders are better off if they invest in the supplier, compared with their profit under the case whereinonly one manufacturer invests. 5） Joint investing is a pure-strategy Nash equilibrium. Manufacturers have incentives to make quality investment in their shared supplier, regardless of thepotential spillover effect. Moreover, stronger spillover effect can help the two competing manufacturers gain more profit. Our findings provide quality investment choices for competitive finns, as well as explain why some of them are still willing to invest in a common partnereven when realized investments may potentially benefit their rivals.