Topic
Measurement: what you can count, and what consent costs you
The consent rules come first here, because they decide what you can measure before a visitor agrees.
Ad platforms can report fewer sales than a business really makes. The gap has two causes, and only one of them can be fixed technically. Knowing which is which tells you whether a piece of work is worth paying for.
These articles put a number on the gap and say which part of it you can get back.