“…On the one hand, some researchers have examined the effects of aggregate word-ofmouth (Chen, Wang and Xie 2011;Chevalier and Mayzlin 2006;Godes and Mayzlin 2004;Zhu and Zhang 2010), online viral marketing activities (De Bruyn and Lilien 2008;Toubia, Freud, and Stephen 2011), and online community participation (Algesheimer et al 2010;Manchanda, Packard, and Pattabhiramaiah 2013;Stephen and Toubia 2010) on aggregate sales. On the other hand, others attempt to establish the casual effects of social interactions on adoption decisions at the individual level (Nair, Manchanda and Bhatia 2010;Nam, Manchanda, and Chintagunta 2010;Zhang 2010). A few researchers examine social interactions in a multiattribute utility framework 1 (Narayan, Rao, and Saunders 2011;Yang and Allenby 2003) or explicitly collect network information (Nair, Manchanda, and Bhatia 2010;Narayan, Rao, and Saunders 2011;Reingen et al 1984).…”