In the Silver Bulletin/FiveThirtyEight tradition, we’ve always given names to our sports models (PELE, ELWAY) — but never to our election forecasts.
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we → give → forecasts
I suppose we’d like to think that our presidential model is renowned enough at this point that it doesn't necessarily need any further identifier.
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it → suppose → identifier
But we’ve decided we do need a name for what we informally call our “midterms model.”
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we → decide → what
That’s because “midterms model” is actually a misnomer.
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model → ’ → ?
The model forecasts both Congressional and gubernatorial races, but it’s trained on both midterm years like 2022 and years where these races coincide with presidential elections.
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races → forecast → elections
So now we’re calling our model FLIPR 🐬 instead.1
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we → call → model
In line with our tradition of silly backronyms, FLIPR stands for Forecast with Leading Indicators, Polls and (Expert) Ratings.
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FLIPR → stand → Indicators
We like this name because it’s sort of a triple entendre:
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it → like → entendre
The principal goal of these elections is flipping individual seats, and ultimately the House and Senate.
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goal → flip → seats
FLIPR is a hat tip to the inherently probabilistic nature of the forecast — we run 40,000 simulations every time the model is updated.
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model → run → simulations
It’s not as simple as “flipping coins”, but the simulations are necessary because of the complex relationships between different types of races.
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simulations → ’ → races
FLIPR essentially consists of three different layers stacked on top of one another: polls, non-polling leading indicators (e.g., fundraising, incumbency) or what we sometimes call “fundamentals”, and then a final layer of race ratings from longstanding outside expert groups like the Cook Political Report.
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we → consist → Report
In fact, there are three versions of FLIPR that correspond to each layer:
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that → be → layer
Lite derives as much information as possible from polls alone;
Classic is polls + fundamentals;
And Deluxe is polls + fundamentals + expert ratings.
While Deluxe is our default version, almost all of the charts and tables on the FLIPR landing page allow you to, uh, flip back and forth between these versions.
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you → derive → versions
The way FLIPR is designed, the expert ratings layer is probably the least important — the proverbial “icing on top.”
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layer → design → top
But if you want a forecast without any expert ratings, we have you covered with Lite and Classic.
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you → want → Lite
I’d say probably not.
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I → say → ?
If you’re a former FiveThirtyEight reader — I retained the rights to all of the models I designed for them per my deal with Disney — you’ll recognize that some of what I’ve just described sounds familiar.
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I → ’re → what
In fact, some of the code in FLIPR just celebrated its 16th birthday, having survived since the first midterms forecast I built back in 2010 when FiveThirtyEight was stationed at the New York Times.
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FiveThirtyEight → celebrate → Times
We think this track record is one of the things that makes FLIPR unique — competing models come and go, succeed and fail, but few have been around long enough to truly have any sort of long-term track record.
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few → think → record
And our midterms forecast performed quite well in both 2018 and 2022.
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forecast → perform → 2018
However, FLIPR and its predecessors have a lot of moving parts.
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FLIPR → have → parts
And we’ve made refinements every year.
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we → make → refinements
While the basic foundation is similar to 2010, nearly every component of the model has been swapped out for a new version at some point.
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component → swap → point
It’s a little bit like the paradox of the Ship of Theseus: if every component of a model has been upgraded at some point, is it still the same model?
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it → ’ → point
The model underwent a near-complete refit in 2018 when the Lite/Classic/Deluxe concept was introduced.
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concept → undergo → 2018
It also underwent another suite of changes in 2022 to reflect increasing political polarization.
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It → undergo → polarization
And even though we really liked the 2022 version of the model, we wound up making more changes and improvements this year (2026) than I was originally expecting — rather than just “turning it back on.”
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I → like → it
These changes have a common theme: they don’t change the underlying structure or philosophy of the model so much as seek to execute on our original design with more precision, robustness, and internal consistency.
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they → change → precision
I have complicated feelings about AI coding tools — and I very much disagree with the idea that they’re a substitute for human judgment.
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they → have → judgment
But as a complement to human judgment, they’re pretty nice.
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they → ’re → judgment
Probably, in fact, they’re better for reviewing and refining an existing model than for building one from scratch.
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they → ’re → scratch
Basically, every single line of code from our 2022 model2 has been audited and, in many cases, improved.
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line → audit → cases
Many of these improvements are not highly visible: they concern things like faster program runtime, better error detection, and better “code hygiene” that makes FLIPR easier to audit and update.
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FLIPR → concern → runtime
But having software that speeds up some of the most tedious aspects of coding also freed up time to test out different hypotheses and clear a long list of items off of our punch list.
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that → have → list
Some of these upgrades fell under a longstanding category of “would be nice to have, if only we had the time.”
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we → fall → time
For example, FLIPR now explicitly simulates ranked-choice voting, as used in Alaska and Maine.
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FLIPR → simulate → Alaska
Building that code took a couple of hours and relied heavily on our expertise; it’s not nearly as simple as telling an AI coder “ok do ranked-choice voting now.”
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it → build → voting
It probably would have taken a couple of days instead of a couple of hours in the world before Claude and ChatGPT, however.
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It → take → Claude
Still, ranked-choice voting is a fairly low-stakes problem since the other 48 states don’t use this process.
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states → rank → process
…and 241 more, not listed.
The Aporia
