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docs(dead-ends): DE-58 — censored (Tobit/AFT) CLint regression does not improve end-to-end Cmax#108

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docs(dead-ends): DE-58 — censored (Tobit/AFT) CLint regression does not improve end-to-end Cmax#108
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@jam-sudo jam-sudo commented Jul 9, 2026

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Summary

Gate-tests the censored-label regression candidate surfaced by the 2026-07-08 deep-research sweep (Svensson et al. 2025, AI in the Life Sciences 7:100128). Verdict: FAIL → DE-58. Headline 2.743 untouched (dev-state experiment, nothing integrated).

Motivation

The CLint training set (clearance_hepatocyte_az.tab) is 27.4% censored (16.1% left-censored at the assay floor CLint=3.0; 11.3% right-censored at the ceiling 150), yet the shipped model (reg:squarederror on log10) treats those piles as exact point labels. Hypothesis: honest censoring recovers extreme-value information and improves the CLint input, hence Cmax.

Method — controlled AFT ablation

Both arms are XGBoost survival:aft (normal distribution = Tobit on log time), identical features (Morgan-2048 + 9 RDKit) and hyperparameters; only label bounds differ, isolating the censoring treatment:

  • AFT-exact — every point lower=upper=Y.
  • AFT-censored — floor → left-censored (0, 3.0]; ceiling → right-censored [150, +inf).

Stage A: per-drug ΔCLint on the 107-holdout. Stage B: feed shipped / AFT-exact / AFT-censored CLint through the full pipeline (predict → engine → meta) on one local stack; compare AAFE.

Result

Stage A — censoring moves CLint materially: median |Δlog10(CLint)| = 0.088 (~22%), 52/107 drugs move >26%, max 3.8× (isosorbide 6.5→1.8). Movers are predominantly low-CLint renally-cleared drugs pushed below the naive floor — exactly where hepatic CLint is not the Cmax-binding term.

Stage B — no end-to-end gain (dev-state, stack-internal Δ):

arm engine AAFE ml AAFE meta AAFE
shipped 4.4127 2.9981 2.6219
AFT-exact 4.2681 2.9981 2.6339
AFT-censored 4.3218 2.9981 2.6294
  • Censoring Δ (AFT-censored − AFT-exact): engine +0.0537 (worse), meta −0.0045 (noise vs CI half-width ~0.42).
  • Per-drug meta: 28 better / 34 worse / 45 unchanged — net wash.
  • Sanity: ml bit-identical across arms (maxdiff 0.0); AFT-exact meta 2.634 ≈ shipped 2.622 → AFT proxy faithful.

Why it fails

Svensson's own conclusion realised on our pipeline (censoring lifts uncertainty/NLL, not point accuracy), and a fresh controlled re-demonstration of three internal walls: §2 error-cancellation (better-motivated CLint breaks the joint balance → engine worse), §8/DE-42 (moved drugs are low-CLint renal cases where F binds Cmax, not CLint), DE-43 (fixed-weight meta damps the engine move, +0.054 → −0.0045). Per §4 the gate precedes integration → not integrated.

Changes

  • docs/research/dead-ends.md — DE-58 entry
  • docs/research/diagnosis.md — §1 censored-regression bullet + external assay-reproducibility refs (Fagerholm 2022; Bowman & Benet 2019)
  • scripts/clint_censored_regression.py — reproducible gate (PYTHONPATH=src, deterministic seed 20260422)
  • data/validation/clint_censored_regression_2026-07-08.json — result artifact

Sanitization guard passes (713 tracked files); ruff clean.

…ot improve end-to-end Cmax

Deep-research candidate (Svensson et al. 2025). CLint training is 27.4% censored
(floor 3.0 / ceiling 150); shipped model treats the piles as exact. Controlled AFT
ablation (XGBoost survival:aft normal; AFT-exact vs AFT-censored isolates censoring):

  Stage A: censoring moves CLint materially (median |Δlog10| 0.088, 52/107 >26%),
           concentrated in low-CLint renal drugs pushed below the floor.
  Stage B (end-to-end, one local stack):
           engine AAFE +0.054 (worse), meta -0.0045 (noise vs CI hw ~0.42),
           per-drug 28 better / 34 worse = net wash.

ml bit-identical across arms; AFT-exact meta 2.634 ~ shipped 2.622 (proxy valid).
Matches Svensson's own finding (censoring lifts uncertainty/NLL, not point accuracy)
and re-demonstrates §2 error-cancellation + §8/DE-42 + DE-43. Not integrated; headline
2.743 untouched (dev-state experiment, state-internal Δ).

- scripts/clint_censored_regression.py: reproducible gate (PYTHONPATH=src)
- data/validation/clint_censored_regression_2026-07-08.json: result artifact
- diagnosis.md §1: censored-regression bullet + external assay-reproducibility refs
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jam-sudo enabled auto-merge (squash) July 9, 2026 01:53
@jam-sudo
jam-sudo merged commit eb2f898 into main Jul 9, 2026
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