What is data drift and how do you detect it?

easy

Answer

$Data drift is a change in the input feature distribution P(X) over time compared to training data.$
$Detect it with statistical tests per feature (KS test for numeric, chi-square for categorical), Population Stability Index (PSI > 0.2 = significant drift), or distance measures (JS divergence, Wasserstein).$
$Monitor drift in production dashboards and alert when thresholds are crossed.$
$Drift does not always hurt performance — measure impact on output and label if available.$

Check yourself — multiple choice

Data drift = change in P(X). Change in $P(y \mid x)$ is concept drift.

#monitoring#data-quality

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