In product-oriented online social networks, members post product reviews as well as maintaining a list of friends. How to measure the influence a member receives from her friends? This study compares four models to measure the influence based on different theories which make various assumptions of member behavior in a social network. An empirical study was conducted based on 2324 social network members of a cosmetic website. We found the influence from a member’s egocentric network is best measured by a model that incorporates both the frequency and valence of interactions among members.