Methodology
How we research and check the numbers
The standards page explains how we grade a claim. This page explains the mechanics — where the figures come from, how they stay honest over time, and what has to pass before a page goes live.
The sources we rely on
We prefer primary sources — the document, spec sheet, or ordinance itself — over aggregators. In order of preference:
Manufacturer documents
Generac and Kohler (Rehlko) spec sheets, warranty terms, and service documents — cited by document number where one exists.
Municipal permit pages
City and village building/permit departments for permit fees, licensing rules, and the issuing office — the authority for anything local.
Utilities
ComEd and Nicor Gas documentation for interconnection, service, and meter-capacity requirements.
Government + safety bodies
U.S. Census (ACS) for demographics, U.S. CPSC for safety data, NFPA 37 for setbacks, the Illinois Commerce Commission for reliability metrics, and NWS for storm records.
Industry sources
Used only where a primary source does not exist, and flagged as secondary — two or more independent citations before a claim is treated as observed.
One evidence file behind the copy
Claims used in the copy trace back to a single internal evidence file. Each entry records the figure, its source, the grade it earned, and the date it was retrieved. Where a source blocks automated access, the entry also carries a public web-archive snapshot so the exact figure can be re-checked later.
Chicago-area pricing is treated as local data and dated as such. National estimates are labeled national, because they typically understate what Illinois labor and permits add to an installed price.
Checks that run before a page ships
Dates must be real and consistent
Every publish and update date is validated as a real calendar date, and an update date can never precede its publish date. A bad date fails the build rather than shipping a dishonest freshness signal.
Local figures can't be copied between cities
Each city's demographic figures must be unique and must carry the exact Census table and geography they came from. If two cities were ever given the same set of numbers, or a figure's label drifted from its source, the build stops.
Freshness reflects content, not deploys
Update dates come from an editorial record of when a page's content last changed — never from the moment the site was last rebuilt — so a redeploy that changes nothing does not falsely mark every page as fresh.
See the editorial standards for how claims are graded, and the corrections policy for how we handle an error.