Data Assessment β€” Critique

Reviewer: explorer-critic Target: quality_reports/data-assessment.md Phase: Discovery (encouraging severity) Date: 2026-05-11

Score

88/100 β€” PASS at the 80 threshold.

Verdict

PASS. Technically sound; measurement validity and identification compatibility are well-handled. Main weakness is the unverified column inventory (tooling constraint, not analytic flaw) and underspecified treatment of measurement error in the headline idiovol construction.

Issues

Minor β€” Tooling: unverified column inventory (-2)

Explorer transparently flagged that it could not execute Rscript. Column inventories match canonical WRDS schemas; no fabricated fields. Routed to data-engineer for confirmation.

Minor β€” Measurement error treatment of idiovol underspecified (-4)

Microstructure noise, bid-ask bounce, low-price filter all covered. Underspecified: estimation noise in residual variance at 17–22 daily obs; beta estimation error in 21-day window; Stein-shrinkage variants. Highest-impact omission.

Minor β€” External validity / regime-break discussion thin (-2)

1990 start is β€œmodern Nasdaq era,” but post-decimalisation cut is 2001. Subsample motivations could be stronger (decimalisation, Reg-NMS 2007, post-2010 ETF growth).

Minor β€” Delisting-return magnitude unsupported (-2)

Limitation correctly identified; Shumway (1997) named. Asserts β€œunlikely to overturn the headline result” without magnitudes (Shumway-Warther: 30-55%; Beaver et al. 2007 shows portfolio impact for small/penny stocks dominating the high-idiovol quintile).

Minor β€” AMEX/ARCA treatment standard but not discussed (-2)

AHXZ-lineage convention. AMEX inclusion consequential for high-idiovol quintile (small, volatile firms). No robustness on dropping AMEX. ARCA migration handling unclear.

Minor β€” Five-month-ahead horizon end-of-sample not discussed (-2)

AHXZ L/M/N notation: end-of-sample truncation effects matter.

Minor β€” Runtime estimates optimistic (-1)

4-8 min for OLS regressions plausible with data.table + lm.fit(); doubles for FF3; 67M-row read is 30-60s; 6-8 GB peak memory on 16 GB laptop is tight.

Minor β€” Compustat currency rule not pinned down (-1)

Should be explicit: curcd == 'USD'.

Summary

Competent Grade-A data assessment for an AHXZ-style replication on a 1990-2024 US equity panel. Measurement validity is sound; sample selection filters are AHXZ-lineage convention; identification compatibility for predictive sorts and Fama-MacBeth is clearly supported. Main weaknesses: underspecified measurement-error treatment and a tooling constraint that prevented direct column-name verification, both explicitly acknowledged and routed downstream. Comfortably clears 80.

Recommendations (not required; for data-engineer hand-off)

  1. Verify column inventory with str(readRDS(...)) on first load.
  2. Pre-specify shrinkage or noise treatment for residual-variance estimator.
  3. Pin down currency filter as comp.funda$curcd == 'USD'.
  4. Quantify delisting-return sensitivity when splicing msedelist/dlst.
  5. Document regime-break robustness pre-specification.
  6. Confirm runtime on actual hardware.
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