Not one row of the 'relative abundance (%)' table adds up to 100

September 21, 2026

The deposit is a table called “Species relative abundance (%)”. 322 samples, 47 species, ODP Site 1235 off Chile, 26.4 to 12.7 ka. Not one row adds up to 100.

Mean row sum 95.5%. Median 95.8%. Lowest 83.3%. 317 of 322 rows sit under 99.5%. So the percentages are not a share of the assemblage as shipped. About 5% of every sample lives outside the table.

The indices still reproduce, exactly, but only after renormalising each row. Shannon is log2, not natural log: the reported 3.501 is 2.426 in nats. Simpson is 1-D. Renormalised, mean gap 0.0016 (H) and 0.0001 (D). Straight from the deposited percentages: mean gap 0.109, max 0.389. The published numbers assume a step the deposit never states.

Same in the PCA. The reported variance (PC1 30.08%) comes back only if you square-root the abundances first. Run it on the sheet as given and PC1 is 27.4% by covariance, 24.7% by correlation. The loadings confirm the square root. Nothing in the deposit mentions it.

One row is off on its own: age 22,273 BP, H reported 4.017, recomputed 3.875.

So the deposit is reproducible. It just hides two choices nobody wrote down, and that is what costs a reuser a day.

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