본 연구는 최근 들어 소매상의 수익에 있어서 매우 중요한 위치를 차지하고 있는 스토어 브랜드 제품의 품질결정에 관해 조사하였다. 이를 위해, 수직적 차별화 모형(vertical differentiation model)에 기초하고 내셔널 브랜드 제품(고급 브랜드 제품과 비고급 브랜드 제품)을 한 개씩 생산하는 두 생산자와 카테고리 전체수익의 극대화를 위해 전략적으로 스토어 브랜드 제품의 품질을 결정하는 하나의 소매상으로 구성된 게임이론연구모형을 설계하였다. 모형의 분석 결과, 스토어 브랜드 제품의 품질결정에 대해 기존의 선행연구들에 의해 논의되어진 생산자의 제품품질결정이나 스토어 브랜드 제품의 수평적 포지셔닝(horizontal positioning)과는 다른 최적 안을 도출하였다. 첫째로, 본 연구의 결과에 따르면 소매상은 스토어 브랜드 제품의 품질을 결정할 때 그 품질수준을 기존의 두 내셔널 브랜드 제품들 사이에 위치시킴으로써 카테고리 전체의 수익을 극대화하여야 한다. 이는 소매상은 소비자들에 의해 가장 선호되어지는 내셔널 브랜드 제품을 겨냥해 그 제품과 유사한 제품을 출시함으로써 수익을 극대화하여야 한다는 스토어 브랜드 제품의 수평적 포지셔닝에 관해 논의한 기존 선행연구들의 결과와 상반되는 것이다. 둘째, 시장상황에 관계없이 (특히 가격에 민감한 소비자들이 상대적으로 많은 시장상황의 경우라 할지라도) 스토어 브랜드 제품이 카테고리 내 가장 낮은 품질의 제품으로 소개되는 것은 최선의 선택이 아니며 비고급 내셔널 브랜드 제품보다 높은 품질의 제품으로 출시되어야 한다. 셋째, 제품의 품질향상이 판매이익의 증가를 가져올 것이라는 일반적인 기대와는 달리, 스토어 브랜드의 경우 심지어 품질에 민감한 소비자들이 상대적으로 많은 시장상황의 경우라 할지라도 그 제품의 품질이 고급 내셔널 브랜드 제품의 품질보다 낮게 책정되어야 한다. 마지막으로, 소매상의 스토어 브랜드 제품품질결정이 생산자의 제품품질결정에 영향을 미치는 원동력(driving force)과는 전혀 다른 원동력에 의해 정해지는 의사결정임을 밝혔다. 생산자의 품질결정에 결정적인 역할을 하는 원동력은 경쟁제품과의 차별화(differentiation)인 반면, 소매상의 경우에는 내셔널 브랜드 제품의 판매로부터 얻어지는 소매상의 판매이익(retail margin)의 증가와 기존의 내셔널 브랜드 제품의 고객들을 수익성이 보다 높은 스토어 브랜드 제품으로 유인함으로 기대되어지는 수익의 증가가 중요한 원동력이 된다. 이러한 결과들을 통해 연구자들과 경영자들에게 제시하는 시사점들을 논의하였다.
The importance of store brands has been growing in retailing. The Private Label Manufacturers Association (PLMA) reports that store brands, or private labels, continue to grow in sales and volume in the U.S. market and account for one of every four items sold every day in U.S. supermarkets these days. Nowadays 90 percent of consumers define store brands as good "brands" as or even better "brands" than national brands in most characteristics. Consequently, many retailers develop and introduce innovative premium store brand products to increase their category profit. This trend has prompted marketing scholars to address various issues related to store brands, such as the factors for store brand success (Dhar and Hoch 1997), the factors for variations in purchasing preferences for national brands versus store brands (Batra and Sinha 2000), and the effect of store brand introduction (Raju et al. 1995, Chintagunta et al. 2003). Nevertheless, no previous study has investigated directly the retailers` store brand quality decision. When a retailer introduces a store brand, making an optimal quality decision for the store brand must be an important strategic issue for the retailer, but little attention has been paid to this issue. Recently, some prior studies analyzed the issue of store brand positioning in the context of category profit maximization. However, the existing theoretical analyses of store brand positioning focus on horizontal differentiation, while empirical studies and anecdotal evidence generally point to vertical differentiation as a more important brand-positioning dimension. On the other hand, many prior studies have investigated the issue of quality decision problem from a manufacturer`s perspective, but it is not known to what extent the findings of the existing product quality decision literature, with its manufacturer focus, provide applicable strategic guidelines for the retailers. In this study, we directly address this deficiency in the literature and explore the following research questions: 1)What is the optimal quality for a store brand, when it is introduced to a category characterized by a nonzero cost of quality? 2) What are the main driving forces shaping this decision? We analyze the problem with a game theoretic model composed of two national brand manufacturers and a retailer, who strategically chooses the quality level of its store brand relative to the established national brand positions to maximize its category profit. Two existing national brands are vertically differentiated. The retailer has three possible options for its store brand quality decision. First, the retailer can introduce the store brand as the lowest quality product within the given category. Second, the retailer can position the store brand in between two existing national brands in terms of quality. Lastly, the retailer can introduce the store brand as the highest quality product within the given category. Considering the three possible options for the retailer`s store brand quality decision, we analyze four different market conditions in terms of diverse distributions of consumers` willingness to pay for quality. This helps us demonstrate the impact of a category-specific environment on optimal store brand quality decisions and identify major driving forces shaping the retailer`s optimal decisions. In order to investigate the difference between the retailer and the manufacturer in terms of major driving forces shaping their optimal product quality decisions, we also analyzed the case where one of the two national brand manufacturers introduces another national brand in addition to the existing national brand, but there is no store brand introduction. The model analysis reveals that the second option, i.e., the retailer positions the store brand in between two existing national brands in terms of quality, is the retailer`s optimal strategy for its store brand quality decision. Our analysis also shows that the optimal decision is consistent across four different market conditions. That is, even in the market where there are a large number of price sensitive consumers, the retailer should increase the quality level of the store brand above that of the low quality national brand, whereas the retailer should introduce its store brand at a lower quality level than that of the high quality national brand even for the market consisting of a relatively large number of quality conscious consumers. These results imply that a major driving force in the retailer`s store brand quality decision is its incentive to maximize a profit-increase coming from two different sources, the enlarged retail margin of the existing national brands and current national brand customers` switching to the more profitable store brand. This force makes the retailer`s quality-positioning problem significantly different from that of the manufacturer. Our results show that, if the high quality national brand manufacturer introduces another national brand, then its optimal quality level is even higher than that of the existing high quality national brand produced by the manufacturer. In contrast, when the low quality national brand manufacturer introduces another national brand, it is the best strategy to set its quality at a lower level than that of the existing low quality national brand. These results indicate that differentiation is a major driving force in the manufacturer`s product quality decision in the presence of competition.