Notes

What went wrong while building these

Each note below is a defect that measurement found and reading the code did not, in a tool on this site. Both changed the tool afterwards. The script that reproduces every number is named in the note, and the fixtures it runs against are in the repository.

Flagged, unadjusted
12/5

stockouts reported where five had been planted, on the same fixture

A Saturday-only SKU
5.9×

more units reported lost than the product had ever sold, from a flat daily rate

Most stockout-cost calculators overstate losses. Here is the arithmetic.

Four measured failures in the obvious way to price a stockout from an orders export. It passed synthetic data with planted answers first, which is what makes the list worth reading: none of these are hypothetical, and each one has a number attached.

· updated Changed Stockout Cost Read the note →
Swept
256

shop configurations, to see how much of the answer was ours rather than the merchant’s

“Some threshold pays”
395%

of shops, moved by one default we had picked — so we took the number out

Every free-shipping threshold calculator invents one number. Ours did too.

A default we had chosen was deciding the answer, and no fixture could have shown that — a fixture agrees with the threshold that was picked by looking at it. The sweep also killed a detector we had already built, and an algebraic correction that was right about the algebra and worse as a predictor.

Refuses

There is no publication schedule here

A note gets written when a measurement changes a tool, which is not something that can be scheduled. Two exist because two measurements have done that. If you want the ones that have not been written up, the rules they produced are in the repository’s CLAUDE.md, each with the failure that bought it.