“…This is a key research priority (e.g., Aral 2011, Godes 2011, Iyengar et al 2011b, Lewis et al 2012, Libai et al 2010. Recent work has documented systematic variations across customers in influence and susceptibility, but, to our knowledge, only in the realm of new product adoption (e.g., Aral and Walker 2012, Goldenberg et al 2009, Hu and Van den Bulte 2014, Iyengar et al 2011a, Katona et al 2011 or outside the realm of new products altogether (e.g., Godes andMayzlin 2009, Trusov et al 2010). Studying social contagion in both trial and repeat facilitates assessment of the effect of peer behavior on two different dependent variables.…”