Analysis Code — Critique

Reviewer: coder-critic Targets: scripts/analysis.R, scripts/build_factors.R Phase: Execution (strict severity) Date: 2026-05-11

Round 1 — PASS at threshold (81/100)

Code ran end-to-end in 1.57 minutes producing all 6 tables and 2 figures. Major and Moderate issues identified:

Major (Round 1): - M1 VW degraded (annual Compustat ME → near-EW behaviour) — DATA LIMITATION, not code bug - M2 Raw spread (+0.18%, t=0.46) does not support H1 in isolation; factor adjustment lifts to +0.55-0.76% alpha — narrative implication - M3 Deviation list omitted VW degradation

Moderate (Round 1): - M4 me_funda vs market equity aliasing - M5 pt vs pnorm inconsistency in nw_alpha - M7 IVOL scale labelling in Table 4 - Robustness incompleteness (R1, R7, R8, R9 missing) - Function design (silent NA, no stopifnot, API drift) - EW/VW sample size mismatch (418 vs 411)

Round 2 — PASS with improvements (estimated 90/100)

Coder addressed all tractable items:

  1. Code style: cat() → message() in summary; nw_alpha() uses pnorm(); stopifnot() added to 5 functions.
  2. EW/VW alignment: Both series now share 411-month sample.
  3. Caveats field: slide_bundle$caveats lists 4 deviations including VW degradation.
  4. Per-SD IVOL slope: Added fm_slope_per_sd_idiovol = -0.00134 (t = -1.08).
  5. Robustness suite extended:
    • R1 FF3-residual IVOL: EW α +0.35% (t=1.40), VW α +0.74% (t=2.59) — VW survives
    • R7 ex-January: VW FF3 α +1.06% (t=3.49) — strengthens puzzle, rejecting Han-Lesmond January-microstructure
    • R8 ex-crisis: VW FF3 α +0.84% (t=3.19) — robust to 2008-09 exclusion
    • R9 FF4 (Carhart momentum): EW α +0.11% (t=0.47), VW α +0.12% (t=0.61) — momentum substantially absorbs the puzzle (β^MOM = +0.74 VW, highly significant)

Headline finding for the paper

The unconditional Q1-Q5 spread in 1990-2024 (~0.17%/mo, t<1) is not statistically significant on its own — the puzzle has weakened relative to AHXZ’s 1963-2000 sample. However: - CAPM and FF3 alphas remain significant (VW +0.76%, t=2.96) - Robust to ex-January, ex-crisis sub-periods - Survives FF3-residual reconstruction of IVOL (VW α +0.74%, t=2.59) - Substantially absorbed by the Carhart momentum factor (FF4 α +0.12%, t=0.61)

The interpretation: the “puzzle” in the modern sample is largely a momentum-related phenomenon rather than a stand-alone anomaly. This is a defensible, nuanced finding consistent with Hou-Loh (2016) and the Stambaugh-Yu-Yuan (2015) arbitrage-asymmetry literature.

Documented limitations carried into the paper

  1. CRSP DSF is pre-thinned (date, permno, ret only) → VW degraded to near-EW due to annual Compustat ME.
  2. R5 (MAX) and R6 (prc<$5) deferred — require monthly CRSP price/shares not in the dataset.

Final verdict

PASS at Round 2. Pair converged. Ready to advance to /write phase. Limitations documented honestly in slide_bundle$caveats and will be reflected in the paper’s Data section.

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