Measurement and evidence
What is attribution in advertising?
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what it means here
Here is what the term means for a UK buyer
The definition above holds anywhere. Buying media in the UK adds the detail below, including where AdBuyMCP does something different.
The distinction between attribution and incrementality is the most consequential one in media measurement, and most reporting blurs it. AdBuyMCP keeps them under separate labels: observed covers outcomes on your own property matched to the campaign's immutable key, with an explicit note that it is correlation, and powered causal is reserved for a geo-lift result that passed its own power check. Two exclusions are enforced in code: the synthetic baseline series never inflates response counts, and nothing dated before the flight can count as a response to it.
How does AdBuyMCP measure response?
Response is read from analytics you already own, Plausible or GA4, through a token you supply, and matched to the campaign on an immutable UTM key. Promo codes, vanity URLs and pixel events count too. The response window opens at the flight start, so nothing that happened before the media ran is credited to it.
The result carries the label observed: the response happened on a property you own and can audit, and it co-occurred with the campaign.
When is attribution enough?
Attribution is a good operating signal. It is consistent, cheap and available daily, which makes it useful for pacing a campaign and for spotting a broken landing page. Last-click, the most common rule, reliably favours search and retargeting, which sit closest to the conversion, over the channels that created the demand.
When a budget decision depends on whether a channel was incremental, the evidence has to come from a powered test with a holdout. A campaign too small or too national to carry one should say so at planning time.
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related terms
These terms sit next to this one
Most confusion in media buying comes from two adjacent terms being used interchangeably, so these are the neighbours worth reading next.
Last-click attribution
An attribution rule that gives all the credit for an outcome to the final advertising touchpoint before it, and none to the rest. Simple, universally available, and systematically biased towards whichever channel sits closest to the conversion.
Incrementality
The share of an outcome that happened because of the advertising, measured against what would have happened anyway. It is measured by comparing an exposed group with a comparable unexposed one, which counting the conversions that followed an advert cannot do.
CPA
The cost of one completed action, whether that is a sale, a lead or a booking, calculated by dividing spend by the actions attributed to it. That makes it entirely dependent on the attribution model underneath.
Evidence provenance
A label attached to a number recording how it was produced, so anyone reading the number can see how strong the evidence behind it is. The number may be reported by the seller, observed on your own property, estimated by a model, or established by a powered experiment.
same group
These terms are also in Measurement and evidence
What you can prove afterwards, and how to tell a number that means something from one that does not.