Testing and incrementality · The test design · Element
The withheld
What is switched off, and where.
The part
What it is
A whole channel in a set of regions is the cleanest design. Partial reductions produce results that cannot be read.
The withheld set has to be large enough to produce a readable signal and small enough that the cost is acceptable.
The smallest level
The attributes it carries
Each attribute is one of the framework’s shared types. What a date is, and how it is written, is defined once for the whole model — the note here says what it means in this particular place.