Why prefer Jensen-Shannon Divergence over KL for drift?
hardAnswer
- is asymmetric + unbounded + undefined when Q=0 for some support.
- JSD = ½ + ½ where M = (P+Q)/2 is symmetric + bounded to [0, ln 2] (or [0,1] with base 2) + always defined.
- Interpretable as square of a distance (√JSD is a metric).
- Bounded scale makes thresholding across features straightforward.
- Standard choice for drift dashboards.
Check yourself — multiple choice
- Random
- KL: asymmetric + unbounded + undefined at Q=0; JSD: symmetric + bounded [0, ln2] + always defined; √JSD is a metric; better for thresholding
- Same thing
- KL is better
JSD: symmetric + bounded + always defined; better than KL for drift.
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