“大促”下电商虚假促销的定价决策与福利分析

Pricing Decision and Welfare Analysis of Deceptive Promotions by Online Retailers under “Grand Promotion”

摘要: 考虑一个完全垄断市场，研究电商平台中商家的促销策略问题。商家可以选择不促销、正常促销，虚假促销(先涨价后降回原价)三种策略。本文构建一个完全信息动态博弈模型，研究分析不同策略下商家的最优定价行为及其对利润、需求与消费者剩余的影响。研究发现：(1) 虚假促销时商品价格的涨幅会抑制商家对其的定价，正常促销时打折力度过大也会降低商品定价。(2) 在两种促销手段中，商家采用虚假促销获得的利润高于正常促销。(3) 从消费者福利角度看，虚假促销虽然能带来正向的消费者剩余，但其数值显著低于正常促销，表明虚假促销存在对消费者剩余的隐性转移效应。

Abstract: Consider a completely monopolized market and study the promotion strategies of merchants on e-commerce platforms. Merchants can choose three strategies: no promotion, normal promotion, and deceptive promotion (raising prices first and then lowering them back to the original price). This article constructs a complete information dynamic game model to study and analyze the optimal pricing behavior of merchants under different strategies and their impact on profits, demand, and consumer surplus. Research has found that: (1) The increase in product prices during deceptive promotions can suppress merchants’ pricing, while excessive discount power during normal promotions can also lower product pricing. (2) Between the two promotional strategies, deceptive promotion yields higher profits for merchants than normal promotion. (3) From the perspective of consumer welfare, deceptive promotion generates positive consumer surplus; However, it is significantly lower than that under normal promotion, indicating an implicit transfer of consumer surplus under deceptive pricing strategies.