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538’s model mystery

Aug 25, 2024, 9:46pm EDT
mediapolitics
538’s polling splash page as of Sunday night.
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The Scoop

The most scrutinized election forecast model in the US is back online after a mysterious month-long hiatus. But its return has raised even more questions among election data nerds.

The 538 model had drawn intense criticism from other analysts — including the site’s founder, Nate Silver — in July, as Joe Biden’s campaign sank but the model continued to show him likely to win. Semafor reported that the model was built to weigh Biden’s incumbency heavily, and to discount state-based polling far before the election.

When Biden withdrew, 538’s model abruptly vanished, then stayed offline for nearly a month.

It reappeared Friday with a forecast showing Harris winning 58 times out of 100. The results largely mirror those shown by other election forecasters, including the Economist.

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The polling world’s Nates (Silver and Cohn), who don’t always agree with each other, both pointed out on Twitter that it appears the model has been altered significantly, and they criticized 538 and its owner ABC News for not explaining the changes to readers.

According to two people with knowledge of the situation, the model has in fact been adjusted, though there has been internal disagreement within ABC over whether and how much to explain those methodological revisions.

Network sources said 538 staff have had the model largely ready for publication for the past several weeks, but were prohibited by ABC News and the network’s communications team from discussing or disclosing many details about the changes publicly.

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