Key design choice: The baseline model uses the yield-curve spread as its only input.
The augmented model deliberately excludes the spread as a standalone feature. Instead, the spread
enters the augmented model only through interaction terms:
Augmented features: CREDIT_Z, CREDIT_CHG3M, NFCI, NFCI_CHG3M, CLAIMS_SIG,
SPREAD × CREDIT_Z, SPREAD × NFCI, SPREAD × CLAIMS_SIG
Why this matters: An inverted yield curve means different things depending on context.
When the curve inverts alongside rising credit stress and tightening financial conditions, that historically
signals genuine recession risk. When the curve inverts but credit, financial conditions, and labor markets
are all calm, the inversion is less meaningful.
By making the spread conditional on macro context, the augmented model can distinguish between these
scenarios. The interaction terms capture this: SPREAD × CREDIT_Z is large and negative when both
the curve and credit stress point to danger, but near zero when only one is alarming.
Model independence: Because the two models measure genuinely different things
(pure term spread vs. macro-financial stress with conditional spread effects), the reliability gate
can meaningfully arbitrate between them. When they disagree, that disagreement carries real information.