About · Baku
About

Built on one person’s data.
Which is the problem.

I am a researcher, and Baku started because I wanted better answers out of my own wearable. Six years in, the hardest engineering has not been the models — it has been everything that follows from having exactly one test subject.

The record

Six years, 1,607 nights.

Baku was written against a real record, not a spec: 1,607 scored nights going back to 2019, 2,100 days with a full set of computed metrics, 8 self-experiments, a watch, and later a ring.

NIGHTS SCORED · 1,607 TOTAL 3241917820175212292214623110242132522126

The gap in 2023–24 is real. A model that only works on tidy years is not a model.

Long enough to be realSix years is enough history to see a baseline drift, a device change, an illness, and a training block that went wrong.
Written against the messy versionMissing nights, a device swap mid-month, naps recorded as sleep. The awkward cases were the specification.
Still one bodyWhich is exactly the thing the next section is about.
The problem

“It works on my data” is not a finish line.

A threshold fitted to my nights is a guess about yours. It is the easiest defect to ship and the hardest to notice, because every test passes — on the one distribution I can see.

The developer is never hurtA gate that opens at 21 nights is invisible to me and is three weeks of broken scoring for someone new.
Constants describe meSo Baku prefers mechanisms that read your distribution over constants fitted to mine. Where a constant is unavoidable, the code says who it was fitted to.
One device is the silent caseNothing contradicts a wrong number when there is only one source. A watch term sat pinned at its ceiling on 82% of nights and it took owning a ring to see it.
What follows from it

Every number carries its evidence.

A number is worth exactly what stands behind it, so Baku shows you both. That principle is not decoration on this product; it is most of the design.

Ranges, not false precisionBiological age carries an interval that narrows as data arrives.
Your own week firstReadiness is built on seven nights of your sleep, so the range it judges you against is yours.
Only what was measuredEvery value comes from a night that was actually recorded. Nothing is invented to fill a gap.
The company

Small, and not looking for a reason not to be.

Baku is made by Mosaic Analytics LLC, trading as Baku Science, in Salt Lake City, Utah.

IndependentNo outside investors, and so no pressure to grow in a direction the product should not go.
No advertisingNothing on the business side benefits from your attention or your data.
Beta in small wavesInvited a couple of dozen at a time, so the first users’ real distributions can be read before the next group arrives.

In Japanese folklore the baku is a dream eater — a guardian that watches over sleep and turns what troubles you into strength. It seemed like the right name.