Our findings cast some doubt as to the existence of putatively discrete alcohol trajectories. And yet, even in the absence of true population subgroups, trajectories may still be useful in research and clinical practice.45,46 Like contour lines on a topographical map, trajectory groups can function as a convenient way of defining elevations (clinical cut-offs) and summarizing changing distributions of alcohol use across development (see Figure 4). However, if trajectories are not capturing literal entities, they should not be reified. In this case, rather than carve nature at its joints, trajectory approaches may carve joints into nature.
