Item responses for the 16 depressive symptom items included in the Japanese survey.

Responses to the 16 items exhibited a common mathematical pattern. The lines for the 16 items intersect at a single point (black arrow) between “rarely” and “some of the time,” while the lines between “some of the time” and “all of the time” decrease regularly. Reprinted from [9]. Image credit: PLoS ONE at https://doi.org/10.1371/journal.pone.0165928.g001.