In an attempt to clarify the role of statistical methods in research and theorizing about crime, this paper reviews common misconceptions identified by Nagin and Tremblay, about the statistical methods of group-based developmental trajectories, specifically group-based trajectory modeling (TRAJ). There is an attempt to resolve whether groups are fact or fiction. The three misconceptions identified are (1) individuals actually belong to a trajectory group, (2) the number of trajectory groups in a sample is immutable, and (3) trajectories of group members follow the group-level trajectory in lock step. In identifying and examining these misconceptions, TRAJ was found to have important uses, but the bigger problem is that criminology seems obsessed with tools rather than keeping its eye on the prize. Where TRAJ has many important uses, researchers are not convinced that massive data mining absent a good idea is going to advance the field of criminology. References