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feature leakage

/ˈfiːtʃər ˈliːkɪdʒ/ - n.

1 [colloq.] The model knew the answer because the answer was in the question.Keep. Punchy.This is the problem.

Working definition

2. When information unavailable at prediction time slips into training, inflating measured accuracy.

Evidence

See also

feature storeA shared shelf where four teams store four columns named 'revenue'.
model driftThe model did not change. The world did, and no one was watching the gap.
model evaluationThe benchmark the model passes, chosen after seeing which benchmark it passes.
training dataWhatever was easiest to export, now load-bearing.