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Research on the trigger mechanism of sellers' review brushing behavior and e-commerce platform's response strategies
本文研究一个高质量线上商家和一个低质量线上商家之间的价格竞争及可能的刷好评行为,假设电商平台能以一定的好评识别率识别出虚假好评,继而屏蔽不诚信商家的所有评论。讨论了仅一个商家选择刷好评和两个商家均选择刷好评时的博弈模型,通过分析均衡解发现:(1) 如果另一个商家选择不刷好评,当且仅当单位刷好评成本系数低于某一阈值且好评识别率低于特定阈值时,商家会选择刷好评;如果另一个商家选择刷好评,商家选择刷好评的条件除上述情形之外,还包括单位刷好评成本系数略高于某一阈值且好评识别率取极端值的情形;(2) 仅一个商家选择刷好评时,该商家刷好评行为对电商平台期望利润的影响取决于刷单量、好评识别率及消费者对被屏蔽所有评论产品质量的平均估值;(3) 两个商家均选择刷好评时,电商平台期望利润与好评识别率之间呈倒U型关系。
Abstract
This paper studies the price competition and potential review brushing behavior between a high-quality online seller and a low-quality online seller. The e-commerce platform detects fake positive reviews with a certain detection rate and penalizes dishonest sellers by hiding all their reviews. We develop game-theoretic models for the cases where only one seller chooses to brush and both sellers choose to brush, and reveal the following findings by analyzing the equilibrium results. (1) If the rival chooses not to brush, the seller chooses to brush if and only if the unit brushing cost coefficient is below a threshold and the detection rate is below a specific threshold; if the rival chooses to brush, besides the above conditions, the seller chooses to brush when the unit brushing cost coefficient is slightly higher than a threshold and the detection rate takes extreme values. (2) When only one seller chooses to brush, the impact of his brushing behavior on the e-commerce platform's expected profit depends on the volume of fake reviews, the fake review detection rate, and consumers' average evaluated quality of the product after its reviews are hidden. (3) When both sellers choose to brush, there exists an inverted U-shaped relationship between the e-commerce platform's expected profit and the detection rate.
对手不刷好评时,低成本且低识别率触发商家刷好评
当竞争对手选择不刷好评时,若单位刷好评成本系数c高于阈值c1i,商家一定不刷好评;若c≤c1i且好评识别率θ≤θ1i,商家选择刷好评;若c≤c1i且θ>θ1i,商家不刷好评。该结论揭示平台识别能力与市场刷单成本共同构成治理约束边界。
仅一个商家刷好评时,平台利润影响取决于刷单量与识别率
仅低质量商家刷好评时,若刷单量nl≤n1l且θ≤θ1,刷好评降低平台期望利润;若nl≤n1l且θ>θ1,刷好评提升平台利润;若nl>n2l,刷好评总是提升平台利润。仅高质量商家刷好评时,影响取决于消费者对被屏蔽评论产品质量的平均估值re与识别率θ。
两商家均刷好评时,平台利润与识别率呈倒U型关系
两个商家均选择刷好评时,随着好评识别率θ的增高,平台期望利润先增高后降低。低识别率区间,提升识别率能显著增加仅一个商家被识别出的概率,此时产品质量评估差异大,平台获得较高佣金收益;高识别率区间,提升识别率增加均被识别出的概率,竞争加剧,平台利润降低。
商家跟进刷好评受成本约束与识别威慑双重影响
当竞争对手选择刷好评时,若单位刷好评成本系数c高于阈值c3i且好评识别率θ处于区间(0,θ3i2],商家会刷好评;若c>c3i且θ取极端值(θ≤θ3i1或θ>θ3i2),商家不刷好评;若c≤c3i且θ≤θ3i2,商家刷好评。表明局部刷单存在时,特定条件会引发更大范围的策略模仿。
核心解释变量
模型主体:一个电商平台、一个高质量商家h与一个低质量商家l组成的供应链博弈系统;核心参数:单位刷好评成本系数c、好评识别率θ、佣金率a、竞争强度ω=1/t、评论数量敏感度φ、消费者对被屏蔽评论产品质量的平均估值re
被解释变量
决策变量:两个商家的产品价格ph、pl,以及刷好评量nh、nl;被解释变量:商家利润πh、πl与电商平台期望利润πp;均衡策略:商家在四种情境(均不刷、仅h刷、仅l刷、均刷)下的刷好评选择
样本与数据
理论模型研究,无实证样本;数值模拟参数设定:a=0.2,vh=0.2,vl=0.4,rh=0.85,rl=0.5,φ=0.1,ω=5,nh=0.2,nl=0.4,re=0.4,分别取c=0.26、0.3、0.05,re=0.5、0.4、0.3进行算例分析
识别方法 / 模型设定
运用Hotelling模型刻画两个商家的价格竞争,构建均不刷好评、仅低质量商家刷好评、仅高质量商家刷好评、均刷好评四种博弈模型;每种情境下考虑平台未识别出与识别出虚假好评两种概率情形,求解子博弈精炼纳什均衡,通过比较商家刷好评与不刷好评的期望利润推导触发条件
内生性及稳健性检验
拓展分析1放松消费者效用线性假设,引入消费者对虚假好评占比的敏感度β及被屏蔽评论产品质量估值的异质性,发现命题结论总体一致,证明模型稳健性;拓展分析2考虑产品差异化足够大、商家成为区域垄断商的情形,发现商家刷好评条件与对手无关,平台利润随识别率单调变化,与基准模型的非单调变化形成对比,凸显市场竞争的影响
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