A paid channel mix audit answers one question: if you moved money between channels tomorrow, would you get more growth for the same spend? A good audit checks how each channel is measured, how much of its reported performance is truly incremental, and where spend has hit diminishing returns. It ends with specific reallocations, not a list of observations.
The five things a paid mix audit should check
- Measurement for each channel. What each channel's numbers are based on: platform reporting, last-click, an MMM or an experiment. Platforms grade their own homework, and their reported conversions often add up to more than your actual total.
- Incrementality. Which channels have been tested with holdouts or geo experiments, and what those tests showed. Branded search and retargeting are the usual places where reported ROAS is much higher than true lift.
- Saturation. Response curves by channel. If the last 20% of a channel's budget brings in almost nothing, that money belongs somewhere else.
- Mix balance. How much spend is in channels that capture existing demand (search, retargeting) versus channels that create it (video, CTV, social prospecting, brand).
- Planning process. How budgets get set and changed. If the mix is mostly last year's plus 10%, the audit should say so.
Signs your paid mix needs an audit
- Platform-reported conversions add up to more than the sales or signups you actually saw.
- Cost per acquisition keeps rising and nobody can say which channel is driving it.
- You've never run a holdout on your biggest channel.
- Finance has stopped trusting marketing's numbers.
- Brand or upper-funnel spend is the first thing cut every quarter because it "can't be measured."
What you should walk away with
An audit should hand you three things. First, a ranked list of reallocations with expected impact. Second, a test plan for the channels where the data can't settle the question. Third, a measurement setup that lets you keep making those calls without an outside consultant.
Who should do the audit?
An agency can audit its own work, but it has a stake in the answer. A platform will audit itself. An independent consultant who doesn't buy media has no reason to protect any channel, which is the main reason to bring one in.
Base Note Data's Measurement Audit covers all five areas above and ends with a prioritized reallocation and test plan.