This preprint presents a methodological framework for analyzing institutional bundles and fertility resilience through threshold estimation using WAIC/LOOIC and SVC diagnostics. The study adapts biostatistical practices—such as Bayesian model comparison, normalized weights, and activation thresholds—to social science contexts where linear models and AIC/BIC remain dominant. Illustrative simulation results demonstrate how childcare, gender equality, and governance transparency operate as mediators and amplifiers once activation thresholds are surpassed. Interaction terms are selected via information criteria, with quantitative guidelines for ΔELPD interpretation provided. All reported values are derived from simulation code and serve as a proof-of-concept rather than empirical evidence. The contribution lies in methodological transparency and reproducibility, offering social scientists a new lens for institutional analysis.