Abstract: Due to the asymmetry of experiential product quality disclosure in e-commerce platforms, it is necessary to design a variety of quality assurance mechanisms to ensure that consumers have the right to know quality information. Previous studies mainly focus on the self-generated quality assurance mechanism such as word of mouth (WOM), but lack systematic researches on the certification-based quality assurance mechanism. This study capitalizes on the opportunity that a quality disclosure strategy adjustment of Ctrip.com in June 2017, using online sales data of outbound tourism products to study the coupling effect between two quality assurance mechanisms and the stimulating effect on online sales. The three main findings are as follows. First, spontaneous-constructed WOM valence has an inverted U-shaped relationship with online sales in the short term of the policy shock. Second, the certification-based quality disclosure mechanism will improve the sales through disclosure transparency in the short term, and in the long term increase the sales through the quality certification level. Third, the two quality assurance mechanisms have different coupling effects at different time, which have an exclusion effect on low-quality products and a cultivation effect on high-quality products. This study improves the classification of quality assurance mechanism and the explanation of its action mechanism, and widens the thinking in relation to product quality governance of the platform.

Key words: experiential product, quality assurance mechanism, quality certification, information transparency strategy, e-commerce platform governance