I · chapter

Data, Measurement & Analytics

What it is: the measurement ruler the rest of the map spends against — how a brand knows what worked, decides what's true, and decides where to spend next under accelerating signal loss. I owns measurement methodology; every other domain owns the thing it measures and consumes I's ruler.
The organizer: not the funnel and not a tidy decision tree, but basis-of-truth × signal-integrity — a causal-certainty ladder (last-click → MTA/DDA → MMM → incrementality) run against a signal-loss gradient. The practitioner's real agony: do I trust the dashboard, the model, or the holdout?
The 2026 shift: the identity layer keeps eroding (Privacy Sandbox fully retired Oct 2025, ATT, consent attrition), so the field has pivoted off touchpoint tracking and back onto modeled and experimental methods — MMM is in a genuine renaissance and incrementality is the apex arbiter.
The non-negotiable: incrementality is the arbiter. No platform-reported ROAS, no server-side-recovered conversion, and no platform-modeled conversion enters as fact. This rule rests on the peer-reviewed economics literature (Lewis-Rao, Gordon et al., Ghost Ads), NOT vendor decks.
Don't: trust a platform grading its own homework, confuse recovered signal with incremental signal, read GA4's "AI Assistant" number as your AI share (it undercounts by an order of magnitude), or quote a vendor lift band as a point estimate.

How this domain is organized internally — and the decision logic, runnable workflows, and agent angle — are in the full map.