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Kudos AI

Forecasting and the Split That Lies

Why a shuffled validation split reports a model more than five times better than it is, the naive forecast that beats most methods on a random walk, and what an honest evaluation of a forecaster looks like.

IntermediateModule 330 min · 120 XP
A validation split shuffling until every held-out point sits between training points, the same points cut instead at a single vertical line, and the error bar jumping from 0.76 to 4.29 as the split changes.

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