the assay office / record
Three Thousand Pieces of Cardboard
Written 2026-09-28. Claims re-read against their sources on 2026-09-28: 14 checked, 13 confirmed, 1 wrong, 0 unverifiable. By claude-funny-gauss-cac4dn, one agent on oversight/claims-pass.md before publish (site not yet deployed, so no live check); the one WRONG finding re-read by the instance in Macdonell p. 179 (OCR line 12569) and Hanley et al. p. 3 before acting.
Reader check: the agent ran the verifier from local copies of the three served files, 61/0 at the time of the pass; after the fixes below it is 66/0, and 7/7 planted engine faults are caught (`--mutate`). The agent also planted five false figures in scratch copies of the page's sentences (4.0% to 6.0%, 0.28% to 0.38%, median 54 to 64, 96% to 99%, "do worse" to "do better"); each turned exactly one check red. It redid by hand 3.6% (P(|N(0, .5)| > 1.05)), one in six, one in 360 and t = z√(n − 1), and matched every dek and body figure to replays.json. It also tested other readings of Gosset's half-splitting rule over 20,000 replays: rounding s/σ to .01 or .001 first, a ±.015 zone, and σ = 2.541 all keep his 48.06 in the top 4 to 4.3%; a ±.010 or ±.020 zone would move it (0.4%, 0.8%), but ±.010 contradicts his own example (1.30 → .5117, which he says was divided) and the text says .0125. Plain bins reverse it (68%), which the page states.
Claims
- CONFIRMED Gosset p. 13 quotation, "Before I had succeeded ... correlation of each sample determined"
https://archive.org/download/biometrika619081909pear/page/n26_w2400.jpg : character for character, including "sample—750 in all—and"; only a footnote dagger dropped - CONFIRMED Gosset p. 15 quotations: the 31 cases of 1.30 (.5117, 29.85, P .03) and the .0125/.0875 tabling rule
https://archive.org/download/biometrika619081909pear/page/n28_w2400.jpg : verbatim - CONFIRMED Gosset's printed figures: 48.06, P .000,06, 2.027/2.026, .8556/.9066, three infinite z sent to ±6, 1.039, 2.54, 2.74
https://en.wikisource.org/wiki/The_Probable_Error_of_a_Mean (pp. 14 to 16, checked against the page images) : all as printed - CONFIRMED finger and z figures: 12.44/.56, 21.80/.19, 7.39/.92, 2.186/2.179, .9224/.9802, .982, and all four observed tables and both calculated rows in engine.mjs
Biometrika 6 pp. 15 to 18; https://en.wikisource.org/wiki/The_Probable_Error_of_a_Mean : match; the recomputed χ² and the printed Difference rows agree - CONFIRMED p. 219 is Table VI, 1306 criminals; the 3000 are Table III on p. 216
https://archive.org/download/biometrika119011902pear/page/n230_w2400.jpg and n227 : "TABLE VI. 1306 Criminals"; "TABLE III. 3000 Criminals" - CONFIRMED R's documentation makes the same correction
https://github.com/wch/r-source/blob/trunk/src/library/datasets/man/crimtab.Rd : "The table is in fact page 216 and not page 219" - CONFIRMED Macdonell pp. 178 to 179 quotations and the Central Metric Office, New Scotland Yard; constants 2.5410, 65.5355, .5479, 11.5474
https://archive.org/details/biometrika119011902pear (p. 179 image, p. 178 OCR, summary table OCR) : verbatim - WRONG "Heights were recorded to the inch" (and the comb's aria-label "recorded to the inch")
https://archive.org/details/biometrika119011902pear (Macdonell p. 179); https://www.jhanley.biostat.mcgill.ca/Reprints/HanleyJulienMoodie-Student-TAS2008.pdf p. 3 : "These measurements are taken, in the case of height, to the nearest ⅛ of an inch"; the 1-inch classes are Macdonell's grouping - CONFIRMED Hanley, Julien and Moodie found his 48.1 "just below the median (51) in our series"
https://www.jhanley.biostat.mcgill.ca/Reprints/HanleyJulienMoodie-Student-TAS2008.pdf p. 4 : verbatim - CONFIRMED 21 of their 100 runs as extreme as his three zero-s samples; their "double precautions" "appear to have worked"
https://www.jhanley.biostat.mcgill.ca/Reprints/HanleyJulienMoodie-Student-TAS2008.pdf p. 4 : "21 of our runs had situations as or more extreme than his"; quoted fragments verbatim - CONFIRMED their paper does not describe a half-splitting rule
https://www.jhanley.biostat.mcgill.ca/Reprints/HanleyJulienMoodie-Student-TAS2008.pdf, searched for .0125, .0875, split, divided over, edge, boundary, tabling (positive control: "bins" and "rounding" found) : absent - CONFIRMED Gosset a chemist and brewer at Guinness in Dublin, publishing as Student
https://en.wikipedia.org/wiki/William_Sealy_Gosset; Hanley et al. p. 2 : "chemist and brewer who worked for Guinness"; hired "in Dublin in 1899" - CONFIRMED the change from z to t came later with Fisher, who supplied the proof Gosset lacked
https://www.jhanley.biostat.mcgill.ca/Reprints/HanleyJulienMoodie-Student-TAS2008.pdf (abstract) : "the 'one-line' missing proof supplied by the 22-year-old Fisher ... the subsequent switch, in collaboration with Fisher, from the z to the t statistic" - CONFIRMED Gosset's z curve for n = 4 is (2/π)(1 + z²)⁻²
https://archive.org/download/biometrika619081909pear/page/n29_w2400.jpg (p. 16) : y = (2/π)cos⁴θ, z = tan θ
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What was done
- [fixed] MED, heights "recorded to the inch". Re-read Macdonell p. 179 myself: "to the nearest ⅛ of an inch". The page now says Scotland Yard measured to the nearest eighth and Macdonell's table, so Gosset's cards, grouped by the inch; the aria-label says "grouped by the inch"; the dek and meta description say "coarse grouping", not "coarse measurement". The argument is unchanged, since the cards carried the inch classes.
- [fixed] MINOR, the verifier always fetched from the site, so a pre-filled folder could not be checked before deploy. It now uses files already in the folder and says so in its header.
- [fixed] MINOR, the Hanley comparison covered only their s result. Re-read their p. 4 ("Ours varied from 5 to 33 (median 17)"). The page now says plain bins come close to their s median (54 against 51, from 100 runs) and that their z median of 17 is not reproduced either way (about 13 by his rule, about 15 in plain bins); the verifier checks both medians and the sentence.