A checklist to audit your last-click setup before you trust a single report

A checklist to audit your last-click setup before you trust a single report

The question: before debating fancier models, is your existing last-click attribution even measuring what you think? Most reporting disputes trace back to plumbing, not philosophy.

Work through this in sequence:

— Confirm the lookback window. A 30-day click window and a 1-day view window produce wildly different channel credit. Write down what's set, not what you assume.
— Check UTM hygiene. Inconsistent casing (Email vs email) silently splits one channel into three. Pull a distinct-source list; anomalies jump out.
— Find the (direct)/none bucket. If it exceeds ~20% of conversions, you have stripped referrers, missing tags, or dark traffic eating real credit.
— Reconcile platform-reported conversions vs your analytics. Each ad platform claims the same conversion under its own rules; double-counting is the default, not the exception.
— Verify cross-domain and subdomain tracking, or sessions fracture at the cart.

The nuance: last-click isn't wrong, it's a convention — it assigns 100% credit to the final touch. That's fine for reconciliation and terrible for budgeting. But a clean last-click beats a sophisticated model built on dirty data. Garbage in, Shapley out.

Bottom line for practitioners: spend a day auditing windows, UTMs, the direct bucket, and double-counting before you spend a month evaluating attribution vendors. Causation questions come later; data integrity comes first.