Vipps is a peer-to-peer mobile payment solution launched by Norway’s largest financial services group DNB. The Vipps transaction data may be viewed as a graph with users corresponding to the nodes, and the financial transactions between the users defining the edges. We have followed the evolution of this graph from May 2015 to September 2016. This is a unique data set, as information about transactions of individuals is usually not available for research. In this paper, we use an advanced statistical model where preferential attachment is combined with fitness. We show that the intrinsic quality of the nodes in the Vipps network plays an important part in the evolution of the network. This insight may, e.g., be used to identify influential nodes for viral marketing.
