Editorial method.

Bellwether is a free, public reference for the ISM PMI suite — Manufacturing (1948→present) and Services / NMI (1997→present) — in its full historical and policy context. Three of the four interactive modes (Timeline, Decompose, Heatmap) cover both reports; only Fed Chair remains Manufacturing-only, because its scenarios pre-date the 1997 launch of the Services PMI. The site is built around a simple editorial commitment: economists disagree, and that disagreement is itself the lesson. Each policy event opens three competing readings — typically a Keynesian, a monetarist, and a third frame chosen for its relevance to that policy.

Where the literature genuinely converges, we say so. Where it does not, we present the best-faith case for each side without picking a winner. The goal is to give the reader enough scaffolding to make their own judgments, not to flatten the debate.

Time-series data comes from four places. FRED (Federal Reserve Bank of St. Louis) supplies industrial production (INDPRO, IPMAN), the effective Fed Funds rate, and the NBER recession indicator. The Institute for Supply Management’s headline PMI composite is the trickier case — FRED removed the ISM series in June 2016 when ISM tightened licensing — so the long historical 1948→August 2014 series is mirrored from forecasts.org (with attribution to ISM as primary origin). The 2014→present headline plus the five subindices plus the per-month industry-level growth lists are scraped from snapshots of ISM’s monthly Report on Business pages on the Internet Archive’s Wayback Machine, so each row links back to the specific archived page it came from. Because Wayback captures of ismworld.org lag the live release by several months, the most recent headline prints come instead from ISM’s monthly press releases on PRNewswire — the URL slug encodes the value and month, the page <title> verifies it, and the row keeps the press-release URL as its citation. Recession peaks and troughs follow the NBER Business Cycle Dating Committee.

Editorial citations on the policy cards and the illustrated timeline at /background point at primary sources where they exist — federalreservehistory.org for chair tenures and Fed-related essays, government release pages from BEA, BLS, and the White House for individual fact citations within policy interpretations, and ISM news releases (live or archived) for the monthly commentary quoted in policy cards. Where ISM monthly comments are quoted, they are attributed and dated.

Per-cell provenance for every number on the site — including which observations are hand-curated vs. scraped vs. synthetic placeholders — is tracked at /about-the-data.

Bellwether is run as a personal project. It is not affiliated with any of the data providers above. The codebase is open and the editorial sources are linked in every policy card. If you spot an error or a missing event, please open an issue.