P-hackle

A daily game about the garden of forking paths.

Every day, P-hackle deals you a synthetic dataset and a ridiculous headline to prove ("Does owning a cat improve cryptocurrency returns?"). Your toolbox is the real one — outcome switching, subgrouping, covariate shopping, outlier surgery, one-tailed tests, optional stopping. You will reach p < 0.05 — the game guarantees it — and then it will show you exactly what you did.

The game cannot be lost. That is the point.

• Sibling of Climatle
• Full specification: docs/implementation_plan.md
• Languages: English · Italiano · Español

Development

Node 22.22.2 or newer, below 23 (.nvmrc pins the major; package.json's engines pins the floor and .npmrc's engine-strict enforces it, so the wrong runtime fails at install with a legible message instead of at test time with 270 unrelated-looking assertion failures).

nvm use                 # reads .nvmrc
npm ci                  # exact lockfile install
npm run dev             # Vite dev server
npm test                # vitest, whole unit suite, ~37s
npm run typecheck       # tsc --noEmit (src, tests, e2e, scripts)
npm run lint            # eslint
npm run build           # production bundle into dist/
npm run bundle          # gzip table + initial-load budget (needs a build first)
npx playwright install chromium firefox webkit   # ONCE, before the first e2e run
npm run e2e             # Playwright; builds and previews the app itself
npm run cal             # calibration: verifies the five §3.9 bands, ~35s
npm run cal -- --write  # …and REGENERATES src/data/p_hit_by_k.json

npm run e2e needs no dev server — playwright.config.ts builds and previews dist/ itself, every run, because the defects it exists to catch only appear after bundling. The full spec set runs on Chromium; e2e/determinism.spec.ts additionally runs on Firefox and WebKit, which is the only way to test the cross-engine claim that Math.exp/Math.log agree.

npm run cal verifies: it recomputes the p_hit table and exits non-zero if the committed src/data/p_hit_by_k.json no longer matches. Only -- --write rewrites that file, and the rewrite belongs in the same commit as the change that caused it.

Three workflows gate the repository:

Workflow	Trigger	What it gates
test.yml	every push / PR	typecheck, lint, the unit suite, the production build, the bundle budget — plus the §3.9 calibration bands when the push touches src/engine/**, src/data/**, src/game/tuning.ts or the simulation script
e2e.yml	every push / PR	Playwright against the real build: the booked-defect suite, the flows, i18n, and cross-realm determinism on all three browser engines
calibration.yml	Mondays 06:00 UTC + manual	the same five bands again, on a schedule, to catch drift caused by something outside those paths — a dependency bump or a Node minor

Prior art

• Aschwanden & King (FiveThirtyEight, 2015), Hack Your Way to Scientific Glory
• Simonsohn, Simmons & Nelson — specification curve analysis
• Gelman & Loken — the garden of forking paths
• Simmons, Nelson & Simonsohn (2011), False-Positive Psychology

License

MIT © Carlos Rodríguez-Pardo