Return on Ad Spend ROAS
For every dollar of advertising you spent, how many revenue dollars came back.
The fork, why two teams get different numbers
ROAS is revenue ÷ ad spend, but the revenue is claimed twice. PLATFORM-ATTRIBUTED
ROAS is what each ad network reports for its own spend, under its own attribution
window and model (Meta on 7-day-click/1-day-view, a search platform on last-click,
a video platform on view-through), and because a single order is browsed across
several of them, every platform claims the SAME sale. Sum the platform ROAS across
channels and you double- and triple-count. The honest counter-number is BLENDED
MER: total revenue ÷ total ad spend, attribution-free. On one DTC brand a month
ran 4.1 "blended ROAS" by summing channel dashboards while true MER was 2.0, the
same demand booked three times.
The trap
Adding channel ROAS together overstates paid performance by counting overlapping and view-through conversions once per platform, and by letting paid claim organic and returning-customer demand that would have converted anyway.
- The full trap, worked on a real export
- Every formula variant, spelled out
- The reconciliation anchor, what to tie it to and when to refuse
Reference: Digital-advertising measurement convention · IAB/MRC attribution & measurement guidelines (reference)