Product quality is an important factor for consumers’ decision making. Consumers’ product-quality perception may differ from firms’ conventional wisdom, which leads the firms to lose a chance to have more profits or have losses. Especially for new products, firms’ misestimation of consumers’ quality perception often happens due to a lack of past data of actual market responses. The firms quickly update their inference on consumers’ quality perception and modify their marketing strategies in such cases, based on test-market data or initial market responses. Such dynamic marketing strategy may lead to endogeneity and biased estimates of the coefficients of strategic variables such as prices in demand models. This paper suggests a simultaneous equation model of demand and supply incorporating the misestimation of consumers’ quality perception and firms’ dynamic marketing strategy as a method to control for endogeneity. We apply the proposed model to the box-office data of Korean movie market and find that the misestimation and resulting endogeneity exist.