Here we test this alternative hypothesis—that statistically-acquired trajectory classes are best understood as gradations on a developmental continuum. Of course, groups can always be created using the rational-construction approach, even when they do not exist in the population—one need only chop the continuum into categories according to a compelling or clinically useful rationale. However, if the true state of development is continuous and distinct trajectory groups do not exist, we will attempt to “triangulate” around the absence of such groups using four methods.
