當廠商策劃在同一個品類下進行新產品引進時，產品線延伸被視為一種低成本，低風險的產品策略。然而，即便廠商同時銷售產品線中多個產品，但往往只針對其中一項重點商品做強力的促銷或廣告的放送。以可口可樂為例，他們持續進行水平的產品線延伸，發展出古典可口可樂(Classic Coke)，健怡可樂(Diet Coke)，和零卡可樂(Zero Coke)三種產品。從實際的觀察中可以發現，可口可樂鮮少同時進行三種產品的促銷和廣告，相反地，他們在每一季促銷中，都會設定某一種口味的產品作為主打。本研究認為，在這樣的產品線廣告策略下，不同產品的購買族群會因為察覺到廠商主打同一產品線中其他產品的產品理念、特色、優點，更容易產生參考價格與購買行為的變化。換句話說，當可口可樂強調零卡可樂的零熱量時，原來的古典可口可樂購買族群可能因此改變對古典可口可樂的購買行為。

本研究結合產品現與參考價格的概念進行實驗。本研究發現，在垂直產品線中，以低階產品作為品牌廣告中的主打產品，會降低高階產品購買者的參考價格；相對的，若以低階產品作為資訊廣告中的主打產品、在廣告中提供低階產品性能的相關資訊，則會提升高階產品購買者的參考價格。然而，在水平產品線中，若僅在品牌廣告或資訊廣告中強調其中一個產品，都有可能降低另一個相關產品購買者心中的參考價格。

Product line extension is considered a low-cost, low-risk strategy of introducing products under the same category. Under product line extension strategy, however, manufactures and retailers usually advertise merely one product during a certain period, rather than advertising all products within the product line at the same time. Taking example of Coke Cola, it keeps extending its product line horizontally in the past years. There are Classic, Diet and Zero Coke belonging to the main product line. As we observed, Coke Cola seldom advertised for three products simultaneously. On the contrary, to highly impress consumers, only one product would be strongly promoted in a certain period. What is interesting is whether the advertisement of Zero Coke lowers the price that Classic Coke buyers are prepared to pay toward Classic Coke while zero calorie is highly emphasized in ads. It would be interesting to investigate the impact of product line advertisement on consumers to see whether the product line advertisement always brings positive influence on reference price toward consumers with different purchase purposes.
This research addressed the question of how product-line advertisement influences consumer’s reference price within vertical and horizontal product line. It combined the research of product line extension and the concept of reference price to give advice for marketing. The category of product used in experiment is durable that was suggested in prior study. To examine the relationship between product-line advertisement and reference price, experimental method was performed here to test different kind of product line advertisement toward consumers with different purpose purposes, buying high-end product, low-end product or one certain product belonging to the horizontal product line. The results indicated that within the vertical product line, the brand advertisement with low-end product decreases the reference price toward high-end product buyers whereas the informational advertisement with low-end product increases the reference price toward high-end product buyers. Besides, within the horizontal product line, both of the brand and informational advertisement with one certain product in horizontal product line decreases the reference price toward the buyer who would like to buy another product belonging to the same product line.

1.Introduction--------------------------------------------------------------------------1
2.Conceptual Model and Hypotheses ----------------------------------------------3
3.Method--------------------------------------------------------------------------------8
4.Discussion ---------------------------------------------------------------------------16
5.Reference ----------------------------------------------------------------------------20

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