Purpose
This article provides an overview of control groups and explains how and why they are used in InnovidXP.
What is a control group?
In scientific research, a control group is separated from the rest of the experiment, so the independent variable being tested has no influence on the results. InnovidXP uses a similar approach: we observe the behavior of households not exposed to ads to estimate expected baseline visit and visitor rates.
How InnovidXP control groups work
The image below shows a spread of households. All the blue circles are households exposed to a brand’s TV advertising in the week a spot airs or in the 30 days prior. The remaining green circles have not been exposed and are eligible to be added to the control group.
Each week, we use a household viewership panel (Inscape in the US and Samba in the UK and DE) to determine which households qualify as unexposed to the brand’s TV advertising. The daily visit behavior of these households forms the baseline for measurement.
How control groups are used
Attribution
The number of visits captured from the control group indicates how many visits we should expect by chance after a spot of a given size.
The difference between the actual number of visits and the expected number of visits forms the incremental attributed response. Daily control visit rates can vary due to seasonal and weekday patterns. For example, Black Friday would show different volumes compared to an average day.
TV Influence
Whilst attribution is calculated at the spot level, TV Influence is calculated at the campaign level. This metric measures the difference between the visitor rate of the exposed group and the visitor rate of the control group across the whole campaign, expressed as an uplift percentage. A TV Influence of 20% means that the visitor rate of the exposed group is 20% higher than the visitor rate of the control group.
Note: Attribution uses control group visit rates, while TV Influence uses control group visitor rates. Attribution applies control groups at the spot level, while TV Influence applies them at the campaign level.
Control group variations
There are variations within the control groups:
Regional control groups
These are filtered by Market Area, so when building control groups for regional campaigns, only households within Market Areas that received impressions are eligible for the control group. The geographical representation of those impressions is matched.
OTT control groups (synthetic spots)
Because there is no single spot with multiple impressions for OTT, synthetic spots must be created by grouping impressions by day, publisher, and creative.
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