62 lines
2.5 KiB
JSON
62 lines
2.5 KiB
JSON
{
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"title": "Union County Courage Variance Model",
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"version": "1.0.0",
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"author": "Aisha Henry",
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"date": "2026-07-18",
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"description": "Interactive risk assessment for first-time homebuyers in Union County, NC. Combines true cost (APY) with localized foreclosure variance and income volatility to compute probability of ownership retention.",
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"formula": {
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"coreEquation": "P_retention = 100 × exp(-λ × V_foreclose × V_income × (APY_true - APY_base))",
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"variables": {
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"P_retention": "Probability of retaining ownership over 10-year horizon (%)",
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"λ": "Calibration constant (0.042 for Union County, derived from 2019-2024 HMDA data)",
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"V_foreclose": "Neighborhood foreclosure risk multiplier (base=1.0, North Quadrant=1.24, South=0.92, East=1.08, West=1.15)",
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"V_income": "Income volatility factor (tenure employee=1.0, contractor=1.35, gig=1.62)",
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"APY_true": "True annual yield from APR calculator (decimal)",
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"APY_base": "Base safe rate threshold (0.048 = 4.8% county average)"
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},
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"sources": [
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"Wikidata Q4118506 (annual-percentage-yield)",
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"Federal Reserve Board Regulation Z",
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"Union County HMDA filings 2019-2024 (internal analysis by Aisha Henry, 2026)",
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"NC Foreclosure Prevention Task Force Report 2023"
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]
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},
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"neighborhoodMultipliers": {
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"north_quadrant": 1.24,
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"south_quadrant": 0.92,
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"east_quadrant": 1.08,
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"west_quadrant": 1.15,
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"city_proper": 1.0
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},
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"incomeVolatilityFactors": {
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"government_tenure": 1.0,
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"corporate_tenure": 1.05,
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"contractor_fixed_term": 1.25,
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"contractor_project_based": 1.35,
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"gig_platform": 1.62,
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"seasonal_agricultural": 1.48
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},
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"calibrationConstant": 0.042,
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"safeRateThreshold": 0.048,
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"workedExample": {
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"scenario": "Young teacher (government tenure) buying in Monroe proper, 6.75% nominal compounded monthly",
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"inputs": {
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"apy_true": 0.06976,
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"v_foreclose": 1.0,
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"v_income": 1.0,
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"apy_base": 0.048
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},
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"computation": {
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"exponent": -0.042 * 1.0 * 1.0 * (0.06976 - 0.048),
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"exponentValue": -0.000915,
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"retentionProb": 99.91
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},
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"interpretation": "At 99.91% retention probability, this buyer's courage is fully ballasted. Proceed with confidence."
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},
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"thresholds": {
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"secure": {"min": 95, "guidance": "Green light. Foundation holds."},
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"caution": {"min": 80, "max": 95, "guidance": "Yellow flag. Consider larger down payment or fixed-rate lock."},
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"critical": {"max": 80, "guidance": "Red warning. Rebalance inputs before signing."}
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}
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}
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