勸服性廣告與研發之基本模型

Abstract

廠商投入勸服性廣告和研發都會擴充消費者的效用。文獻上討論勸服性廣告和研發的影響時，通常并不對兩者進行區分。在本文中，勸服性廣告和研發被區分開來，關鍵點在於勸服性廣告帶來的效用擴充并非長期可持續，因爲勸服性廣告實質上並沒有改變產品本身，進而真正增加消費者的效用。本文從廠商和社會計劃者的角度探討獨占性競爭產業勸服性廣告和研發兩種行爲所產生的效用擴充，研究廠商和社會計劃者選擇投入的勸服性廣告和研發有何不同。通過比較可得，在一期模型中，兩者做出相同選擇。如果考慮勸服性廣告會產生衰減，在消費者效用為CES函數的情況下，兩者的選擇與替代彈性有關，一般並不相同。本文還進一步考察了兩期模型下兩種行爲所產生的效用擴充，在一定條件下，廠商和社會計劃者一般也會做出不同選擇，選擇的結果可能與廠商競爭的激勵程度相關。

Both persuasive advertisement and R&D will enhance the utility of consumer. In the persuasive advertisement and enhancing R&D literature, persuasive advertisement is not distinguished from R&D. This paper considers the difference between these two behaviors. The key point is that the enhancement of utility due to persuasive advertisement is sustainable because it does not make the product better which can increase consumer’s true utility. The paper discusses the enhancement of utility due to persuasive advertisement and R&D in the view of firm and social planner in monopolistic competition industries and investigates the difference between the choice of firm and the choice of social planner. By contrast, firm and social planner make the same choice in one period model. Considering the attenuation of persuasive advertisement, if the utility of consumer is the form of CES function, they make different choices according to the elasticity of substitution. The paper also investigates the enhancement of utility due to the two behaviors in two periods model. Under some certain conditions, we find that firm and social planner make different choices and the result may be associated with the degree of competition in the market.