Methodology · Midterms 2026

Where every number comes from

Each chart, its data, what we did to it and where it can mislead. Every dataset is stored with a content hash, its receipt, so any figure can be recomputed from the same rows.

Chart	Data	Method	Limits
Tipping scale and ballot	Group margins for 2020 and 2024 (presidential) and 2026 (House) as published in a widely shared reference chart; group shares of 2026 voters from the NBC News/SSRS exit poll.	Margins read from pixel positions (about ±1 point). A group's push on the national margin = its share × its swing. The balance point is the share-weighted average margin; the tilt is the turning force around Even, capped at 6°.	Exit polls are estimates; subgroup error runs to several points. Shares are held at their 2026 values, so the balance ignores changes in who turned out.
The bill (receipt)	NBC News/SSRS exit poll, top-issue question and issue items; 122.7m ballots (state tallies compiled by Al Jazeera).	Net votes per issue = share naming it × (D% − R%) × ballots. Because the top-issue shares cover every voter, the lines add up to the national margin.	Says how issue voters split, not what caused their vote. "Also on the tab" items overlap and are not added.
The kerb	NBC News/SSRS exit poll crosstabs.	Margin = D% − R% per group; the band marks ±6 points.	Groups overlap; small groups (4–5% of voters) carry wide error.
Covers	GDELT DOC 2.0, US English-language sources, 5 Aug–4 Nov 2026, collected by Brantopic.	Daily matching articles ÷ all articles GDELT read that day. Brantopic's quasi-Poisson gate flags days above a 0.1% false-alarm bound, with a 28-day minimum baseline. Cover lines are headlines from each issue's busiest day.	Keyword queries miss some stories and catch some off-topic ones. GDELT covers what it crawls, not all news.
Blue wave city	The Downballot's 2024 presidential results on the 2026 district lines; CBS News's list of flipped seats (5 Nov).	Uniform swing: a seat is under water when the national shift exceeds Trump's 2024 margin there. Tower layout (shore to inland by margin) is for legibility only.	Dozens of races were uncalled on 5 Nov. Incumbency and candidates make real seats depart from uniform swing.
Texas relief	Decision Desk HQ county results (2026 Senate, 2024 President, 2022 turnout); us-atlas county shapes.	Swing = 2026 Senate margin − 2024 presidential margin. Height ∝ swing; colour = 2026 margin or ballots against 2022.	Senate against President, so part of the swing is the candidates. 41 counties were still counting on 5–6 Nov.
Convention hall	NBC News/SSRS exit poll: recalled 2024 vote × 2026 House vote.	990 seats, each 0.1% of voters. Turnout effect = margin with the actual 2026 mix of Harris and Trump voters minus the margin with the 2024 mix, holding loyalty rates fixed.	People misremember their past vote, usually toward the winner. To be checked against voter files (Catalist, L2) in 2027.
Topline	Network projections (NBC, CBS, CNN, Yahoo/Newsweek), Al Jazeera turnout, AdImpact spending.	Taken as reported on 4–6 Nov.	Preliminary until states certify in December.

Sources

Brantopic

The Receipt, every Friday.

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