Marc-André Bombeck ac86199808 fix(stats): one standard deviation with its kind named at the call site ...

About a dozen hand-rolled spreads each picked population or sample
variance without saying so, and the two surfaces a person compares
picked differently: the series API reported the population SD of a
blood-pressure series, the MCP tools and the AI payload the sample SD of
the same readings, about 22 % apart at three readings.

`lib/stats/spread` holds `variance` and `standardDeviation` with an
explicit `population | sample` kind and `READING_SPREAD`, the kind every
surface uses to report the spread of a person's readings. The series
route and the feature payload both report it; the spreads that feed a
verdict (the normal-swing checks, the changepoint threshold) and the
clinical glucose SD stay the sample estimate, now said out loud. A guard
fails on a new hand-rolled spread and on the two surfaces drifting apart.

2026-10-20 04:36:54 +02:00

..

__tests__

fix(stats): one standard deviation with its kind named at the call site

2026-10-20 04:36:54 +02:00

spread.ts

fix(stats): one standard deviation with its kind named at the call site

2026-10-20 04:36:54 +02:00