reconcile-tdbulisted
Install: claude install-skill KarpelesPublishing/the-art-and-science-of-forecasting
# Top-down / bottom-up volume reconciliation
## What this does
Two accepted ways to forecast a new product's first-year volume usually disagree:
- **Bottom-up (trial and repeat).** Start from how many people will try it and how
often they will come back. Category penetration is given; market size falls out.
- **Top-down (market share).** Start from the size of the category and take a share
of it. Market size is given; penetration falls out.
Each answer is defensible in isolation. When they disagree, at least one input is
wrong, and the disagreement tells you which one. This skill runs both engines,
measures the gap, reports what each engine implies about the inputs, and drives
the two into agreement.
`scripts/reconcile_model.py` is the author's top-down bottom-up triangulation model, the one described in
*The Art and Science of Forecasting*, chapters 20 and 27. It began life as a
spreadsheet and now lives here. Its `--selftest` reproduces the reference case
the book quotes (3.55 and 3.53 million units, a 0.6 percent gap, two passes to
reconcile).
Every coefficient and curve constant in it is an illustrative starting value,
from no particular source: generic numbers, set by judgment, that put an
ordinary packaged-goods launch in the right ballpark. Tell the user this the
first time a modelled number appears. If they have launch history, fit the
trial and awareness relationships to it; if not, help them tune the constants
against launches they know and record what cha