Measuring Brand Community Strength Figure 8. Plot of CG and the recommendation success rate> bonds." Forman, Ghose, and Wiesenfeld (2008) report a relation between reviews and sales from the identity disclosure perspective. Our study is inspired by these findings, which have provided a general model to explain the emergence and strength of brand communities. The result indicates that a strong brand community accelerates product diffusion. This confirms the importance of brand community and brand blogs. This chapter contrib- utes to brand community research by providing the impact of dense social network among brand communities for successful product propagation. FUTURE RESEARCH DIRECTIONS In this section, we discuss future and emerging trends in the related research. Our future works include improvement of the model of trust and preference. We assumed and validated that the trust relation is developed between users based on their mutual similarity. However, similarity might not be the only reason for building a trust relation. There might be various reasons for social bookmarking: friendship, admiration, reward, etc. Earlier research on personal influence that has examined the relational context includes two contradictory arguments: one supporting the power 648 of similarity and the other supporting the power of heterophily. The results of earlier studies that emphasize the power of similarity in social influ- ence were discussed in the preceding section. What we have not analyzed is the power of heterophily. Rogers (2003) states that heterophilous commu- nication has a special informational potential, even though it might rarely be realized. Gatignon and Robertson (1985) argued that heterophilous influences beyond the boundaries of the social system are common among innovators. The opin- ion leadership literature also places emphasis on heterophilous influences because opinion leaders are special consumers who are heterophilous; that is, they differ from ordinary people (Katz & Lazarsfeld, 1955; King & Summers, 1970). Results of earlier research suggest that both heterophily and similarity drive WOM commu- nication. When a WOM sender and a receiver are similar, the sender is unlikely to have more knowledge than the receiver. Consequently, a WOM receiver is more likely to be exposed to new ideas when interacting with a WOM sender who is dissimilar, but at some point the difference becomes so great that communication suffers. This suggests the possibility of optimal heterophily (Yamamoto & Matsumura, 2009).