A system for collecting data regarding network behaviors of users is disclosed. In one embodiment, the system combines session records of users with corresponding transaction records reflective of e-commerce transactions. The session records may, for example, be generated by one or more collection engines deployed by one or more Internet Service Providers. The transaction records may, for example, be obtained through interactions with one or more merchant web sites. By combining these two types of information, the system can, for example, identify a set of user actions that led to a particular purchase transaction.