// Tab 08 — The Counterfactual // Extension 02: 500-trajectory ensemble — "What if the GI Bill had been fair?" function TabCounterfactual() { const cf = useData('data/counterfactual_ensemble.json'); const [hoveredYear, setHoveredYear] = React.useState(null); if (!cf) return (
Loading ensemble data...
); const { meta, bands, sample_paths, actual } = cf; // Chart dimensions const W = 900, H = 400; const pad = { top: 30, right: 30, bottom: 40, left: 60 }; const plotW = W - pad.left - pad.right; const plotH = H - pad.top - pad.bottom; const yearMin = 1940, yearMax = 2024; const yMin = 15, yMax = 85; const x = yr => pad.left + ((yr - yearMin) / (yearMax - yearMin)) * plotW; const y = val => pad.top + plotH - ((val - yMin) / (yMax - yMin)) * plotH; // Build band polygons (outermost to innermost for layering) const bandLayers = [ { lo: 'p5', hi: 'p95', opacity: 0.08 }, { lo: 'p10', hi: 'p90', opacity: 0.10 }, { lo: 'p25', hi: 'p75', opacity: 0.14 }, ]; function bandPoly(loKey, hiKey) { const fwd = bands.map(b => `${x(b.year)},${y(b[hiKey])}`); const rev = bands.slice().reverse().map(b => `${x(b.year)},${y(b[loKey])}`); return [...fwd, ...rev].join(' '); } // Median line const medianLine = bands.map(b => `${x(b.year)},${y(b.p50)}`).join(' '); // Actual lines const whiteLine = actual.map(d => `${x(d.year)},${y(d.white)}`).join(' '); const blackLine = actual.map(d => `${x(d.year)},${y(d.black)}`).join(' '); // Sample paths (thin ghost lines) const sampleLines = sample_paths.map(path => path.map(d => `${x(d.year)},${y(d.rate)}`).join(' ') ); // Gap polygon: area between black actual and counterfactual median const gapPoly = [ ...bands.map(b => `${x(b.year)},${y(b.p50)}`), ...actual.slice().reverse().map(d => `${x(d.year)},${y(d.black)}`), ].join(' '); // Y-axis ticks const yTicks = [20, 30, 40, 50, 60, 70, 80]; // X-axis ticks const xTicks = [1940, 1950, 1960, 1970, 1980, 1990, 2000, 2010, 2020]; // Hover interaction const handleMouseMove = (e) => { const svg = e.currentTarget; const rect = svg.getBoundingClientRect(); const mx = e.clientX - rect.left; const svgScale = W / rect.width; const scaledX = mx * svgScale; const yr = Math.round(yearMin + ((scaledX - pad.left) / plotW) * (yearMax - yearMin)); const snapped = bands.reduce((best, b) => Math.abs(b.year - yr) < Math.abs(best.year - yr) ? b : best, bands[0]); setHoveredYear(snapped.year); }; const hoveredBand = hoveredYear ? bands.find(b => b.year === hoveredYear) : null; const hoveredActual = hoveredYear ? actual.find(d => d.year === hoveredYear) : null; return (
{/* Confidence label */}
● SPECULATIVE Counterfactual ensemble — not a prediction, but a measure of what discrimination cost
{/* Main chart + sidebar */}
{/* SVG Chart */}
Black Homeownership Rate — Actual vs. Counterfactual Ensemble, 1940-2024 setHoveredYear(null)}> {/* Grid lines */} {yTicks.map(v => ( {v}% ))} {/* X-axis labels */} {xTicks.map(yr => ( {yr} ))} {/* GI Bill intervention line */} GI BILL 1944 {/* Fair Housing Act */} FAIR HOUSING 1968 {/* Fan bands */} {bandLayers.map((layer, i) => ( ))} {/* Gap shading between CF median and Black actual */} {/* Sample paths */} {sampleLines.map((pts, i) => ( ))} {/* Counterfactual median */} {/* White actual */} {/* Black actual */} {/* End labels */} {(() => { const lastA = actual[actual.length - 1]; const lastB = bands[bands.length - 1]; return ( White {lastA.white}% CF {lastB.p50}% Actual {lastA.black}% ); })()} {/* Hover crosshair */} {hoveredYear && hoveredBand && hoveredActual && ( )} {/* Hover tooltip */} {hoveredYear && hoveredBand && hoveredActual && (
{hoveredYear} White: {hoveredActual.white}% Black actual: {hoveredActual.black}% CF median: {hoveredBand.p50}% CF range: {hoveredBand.p5}% - {hoveredBand.p95}% Cost: {(hoveredBand.p50 - hoveredActual.black).toFixed(1)}pp
)} {/* Legend */}
{[ { color: 'var(--ink)', label: 'White actual (dashed)', dash: true }, { color: 'var(--grade-d)', label: 'Black actual', dash: false }, { color: 'var(--gold)', label: 'Counterfactual median', dash: false }, { color: 'rgba(201,168,76,0.3)', label: '90% fan (500 trajectories)', dash: false, box: true }, ].map((item, i) => (
{item.box ? ( ) : ( )} {item.label}
))}
{/* Sidebar stats */}
{/* The Cost */}
The Cost of Exclusion
{meta.gap_closed_pp.toFixed(1)}pp
Homeownership gap attributable to GI Bill discrimination
~${meta.implied_wealth_gap_trillions}T
Implied wealth never built
{/* 2020 Snapshot */}
2020 Snapshot
{[ { label: 'White actual', value: `${meta.actual_white_2020}%`, color: 'var(--ink)' }, { label: 'Black actual', value: `${meta.actual_black_2020}%`, color: 'var(--grade-d)' }, { label: 'Black counterfactual (median)', value: `${meta.cf_median_2020}%`, color: 'var(--gold)' }, { label: 'Actual gap', value: `${meta.actual_gap_2020}pp`, color: 'var(--grade-d)' }, { label: 'Counterfactual gap', value: `${meta.cf_gap_2020.toFixed(1)}pp`, color: 'var(--gold)' }, ].map((row, i) => (
{row.label} {row.value}
))}
{/* Ensemble params */}
Ensemble Parameters
{[ { label: 'Trajectories', value: meta.n_trajectories }, { label: 'Intervention', value: meta.intervention_year }, { label: 'Access fraction', value: `N(${meta.access_fraction_mean}, ${meta.access_fraction_std})` }, { label: 'Confidence', value: meta.confidence }, ].map((row, i) => (
{row.label} {row.value}
))}
{/* Methodology */}
Methodology · Counterfactual Ensemble

The question: What does Black homeownership look like in 2020 if the GI Bill of 1944 had been administered without racial discrimination?

The model: Each of 500 trajectories draws an access fraction from N(0.85, 0.08) representing the share of white homeownership gains that Black veterans would have captured under fair administration. This is not 1.0 because structural barriers beyond the GI Bill (income gaps, geographic concentration) would persist even without lending discrimination. Per-period noise N(0, ~1.5pp) and a compounding wealth-transfer effect account for uncertainty and intergenerational accumulation.

The compounding effect: Homeownership creates equity. Equity enables down payments for children. The longer the counterfactual homeownership rate exceeds actual, the more this intergenerational wealth transfer compounds forward.

Wealth estimate: The implied wealth gap uses median home equity (~$255K) and an estimate of ~195K Black households per percentage point of homeownership. This is a rough lower bound.

This is labeled SPECULATIVE. It is not a prediction. It is a structured way of measuring the scale of what discrimination cost, using the white homeownership trajectory as the natural experiment baseline.

); } window.TabCounterfactual = TabCounterfactual;