PersonalPredictionEngine has thirty constants and no way to tell which
kind each is. Both are argued for in comments, in the same voice, so the
difference is invisible: MAD_TO_SCALE was tuned against fixtures and can
be retuned by anyone with a measurement, while FERTILE_DAYS_BEFORE_-
OVULATION is a claim about how long sperm survive and cannot.
SCIENCE.md is that line, with a verdict and a citation per constant:
supported, needs-a-caveat, contradicted, or not-a-scientific-claim. The
last category is listed deliberately, so nobody demands a citation for a
tuning parameter and nobody mistakes one for physiology and refuses to
tune it.
It is a sibling of architecture/README rather than a section in it. That
document's subject is the module graph, and it fires its review trigger on
a new Gradle module or a changed Room entity; the evidence for a luteal
phase changes when somebody publishes. Two subjects with unrelated review
cycles in one document means the one nobody is looking at goes stale
behind the one they are.
One value changed as a result. POPULATION_DEFAULT_DAYS -- the single
length assumed for a user with one confirmed period and no interval yet --
moves 28.0 to 29.0. Twenty-eight is the number everyone knows and the
large app-data studies agree it is not the average; the mean sits near 29
and only a minority of women average 28. The app's one unavoidable guess
is now the population's actual centre rather than folklore's.
BaselinePredictionEngine keeps 28.0: it is the frozen control, and moving
it would move the yardstick.
The luteal phase is filed rather than changed (#56). Fourteen is above the
measured mean of 12-13, but moving it shifts what the fertility screen
shows every user -- a product decision with its own evidence and QA, not a
line inside a calibration change.
Also fixes the one user-facing claim that outran its measurements. The
Insights banner told a user one cycle in that "a few more and the
predictions get noticeably better" -- an accuracy promise made before a
single forecast had been scored, and for a woman whose cycles genuinely
vary, one the engine can never keep: her forecast gets more honest, not
more precise. It now promises the mechanism, which is true by
construction and is the standard the rest of that screen already meets.
closes#54closes#55
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
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