A Theoretical Framework for Statistical Evaluability of Generative Models
summary
Statistical evaluability is formalized: some metrics are impossible to test from finite i.i.d. samples while others are. Concrete findings: KL and Rényi are not weakly evaluable (perplexity cannot reliably recover TV or restricted KL), and simple precision/hallucination is also not evaluable. A broad family—integral probability metrics (IPMs)—is evaluable when the test class has finite VC or fat-shattering dimension; otherwise IPMs are only 3-weakly evaluable and the factor three is optimal. Proofs use density‑estimation proxies and a new covering argument that tightens uniform‑convergence constants to two.
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chapters (13)
- 0:00Statistical evaluation intro
- 2:32When to use evaluability
- 5:03Defining evaluability
- 9:01Evaluability vs loss minimization
- 11:16Evaluability of perplexity & KL
- 13:48Precision & hallucination rates
- 17:58Test-based vs IP metrics
- 23:02IPM dichotomy by VC & fat-shattering
- 30:36Lower bounds for IPM evaluability
- 36:48Uniform convergence & covering numbers
- 37:32Summary of evaluability results
- 39:38Open problems
- 40:05Q&A
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