The Historical model replays the 1928–2025 annual record, and how it samples those years changes what risk survives. One sampler covers it, with four presets along a single dial, ranging from fully contiguous to fully shuffled.
- Block bootstrap (default). Splices random multi-year runs of the record together. Keeps sequence-of-returns risk (bad years arriving in clumps) while generating many distinct paths, and breaks the single-period regime tailwind. Average block length is the dial: 5–10 years ≈ a business/rate cycle; toward 1 it approaches IID, toward your horizon the contiguous lens.
- Random restart. One continuous run from a random start year, wrapping at the end of the record. Real sequences, more of them than the fixed windows, but each path is still a single contiguous regime.
- Contiguous windows. Replays every overlapping full-length window. This is the classic historical lens: coarse (few paths), and measurably the optimistic outlier: every full window carries the 1980–2020 falling-rate bond tailwind.
- Non-chronological (IID). Draws each year independently. This destroys sequence-of-returns risk and flatters success rates. It is a contrast baseline, never a planning default.
The blurbs above make falsifiable claims, and the test suite pins them structurally. For example, tests verify that contiguous replay is byte-identical to the original lens and that IID kills autocorrelation. If the engine drifts from the description, a test fails.