Two models: The baseline uses the yield-curve spread as its only input — the classic
Estrella-style recession probit. The augmented model is an additive macro-finance specification: the same spread
plus five broader stress measures.
Augmented features: SPREAD, CREDIT_Z, CREDIT_CHG3M, NFCI, NFCI_CHG3M, CLAIMS_SIG
Why additive — and why not interaction terms: An inverted curve plausibly means different
things depending on context, so we tested an explicit interaction version — letting the spread's effect bend
with credit stress, financial conditions, and labor markets (SPREAD × CREDIT_Z, and so on). In a controlled
out-of-sample validation those interaction terms added no distinguishable value: the elastic-net shrank them toward
zero and kept the plain spread as the dominant signal, and the variant that dropped the standalone spread was
actually less well calibrated. The deployed model therefore stays additive.
What this buys: The additive model is simpler, better calibrated out-of-sample, and matches the
specification in the accompanying paper. The reliability gate still has a meaningful job: the baseline reads the
curve alone, the augmented model reads the curve in the company of broader stress, and the gate learns which read
has been more trustworthy over time.
Regularization: The elastic-net's L1 penalty shrinks unhelpful coefficients toward zero, so the
macro features have to earn their place. All inputs are constructed to be leakage-free as of each scoring date.