Figure 3.

Illustrating colliders with a directed acyclic graph and the unintended consequences of adjusting for colliders. (A) A scenario is shown in which there is direct effect of facial injury on an incident temporomandibular disorder (TMD) and pressure pain threshold is depicted as a collider. (B) A scenario is shown in which there is no direct effect of facial injury on incident TMD and pressure pain threshold is a collider. (C) Study participation is depicted as a collider. (D) Contact sport is a collider as well as a confounder of the association between facial injury and TMD. SES, socioeconomic status.