When products receive reviews across platforms: Studying the platform concentration of electronic word-of-mouth

A product can receive Electronic Word-of-Mouth (eWOM), e.g., user reviews, at both retail and review platforms, with considerable variance in volume and valence. We define such eWOM variation across platforms as the platform concentration of eWOM. A lower platform concentration is measured by a higher level of volume equality and valence equality, i.e., a more comparable number of user reviews and more consistent average ratings among multiple platforms, respectively. Results from multiple models over software data from retail and review platforms shows that volume equality and valence equality positively interact to affect online users’ product adoption decisions.