Measurement and evidence
What is statistical power?
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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 concept that separates measurement from theatre, and the one almost no media platform surfaces. AdBuyMCP computes it before running a lift test, defaulting to 80% power at 5% significance on daily observations, and refuses to proceed when the design falls short, returning the days of post-exposure data the test would actually need and the minimum lift it could detect. The refusal is the feature: an underpowered result is a random one, and a random number in a board pack is indistinguishable from a real one.
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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.
Minimum detectable effect (MDE)
The smallest true effect a test could reliably detect, given its sample size, the variance in the data and the power the design was set to. Effects smaller than the MDE will usually be missed even when they are real.
Geo-lift test
An experiment that runs advertising in some geographic markets and withholds it from comparable others, then compares outcomes between them. It can measure what the advertising caused without a login, a pixel or a match rate.
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.
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.