published null · 2024-01 → 2026-06 · verdict: HYPOTHESIS FAILED — PUBLISHED AS A METHODS LESSON
The naive claim: trade migrates from China to Vietnam in proportion to the tariff-rate spread between them. Registered test: bucket shared HS6 codes by 2026 rate spread; the claim requires Vietnam-growth to rise monotonically with spread. Registered 2026-08-09.
Vietnam grew fastest (+170%) where the spread was smallest (<5 points) and China fell 38–53% in every bucket regardless of spread — the monotone relation the hypothesis requires is absent. Diagnosis: the biggest China→Vietnam moves (laptops, phones, telecom) happened in goods where China was barely tariffed at all — anticipation and supply-chain hedging, not collected duty. And the metric itself misleads: rate-on-dutiable is computed on a rounding error whenever the duty-free share is high, producing plausible-looking spreads on codes where almost nothing pays duty. A genuine rate-driven dodge exists in a smaller, duller set (cables, valves, transformers). The lesson is printed as method rule: burden and rate-on-dutiable are different instruments; quoting the wrong one manufactures findings.
| China−Vietnam rate spread | HS6 codes | Vietnam growth | China change |
|---|---|---|---|
| under 5 points | 65 | +170% | −53% |
| 5–12 points | 88 | +6% | −47% |
| 12–20 points | 26 | +52% | −52% |
| over 20 points | 120 | +29% | −38% |
A positive monotone spread→growth relation would have confirmed the original hypothesis; the measured relation is non-monotone with its largest value in the lowest bucket.
This study is a frozen artifact: the ruling and its exhibits do not change when new data lands. If the verdict is ever revised, the revision is printed here with its reason, and the original stays on the record.
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