“…(Quality-price-ratio utility, Xie et al, 2021) The QPR of seller 𝑖's products can be defined by 𝑉 𝑖 = 𝛼 ̂𝑖𝛿 𝑝 𝑖 𝛾 , where 𝛾 > 1 measures the price sensitivity of consumers on the EP. Furthermore, the QPR utility of seller 𝑖's products can be defined by 𝑈 𝑖 = 𝑉 𝑖 𝜉 𝑖 , where the random variable 𝜉 𝑖 reflects the consumers' heterogeneous tastes for seller 𝑖's products.…”