Third, we correlated the dimensions of depressive experience and depressive symptoms with
interpersonal problems. The Structural Summary Method (SSM) was used to confirm, or “locate,”
the interpersonal nature of these variables (Gurtman, 1992; Zimmermann & Wright,
2014). The SSM builds on the fact that the octant scales of an IPC measure correlate with
each other following a sinusoidal wave form, and that the same can be expected for correlations
with external measures. The pattern of correlations between the IIP eight octant scales and an
external measure (e.g., DEQ self criticism) can be modeled by the following equation: