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What are Ghost Bids and Ghost Ads? An Explanation of an Emerging Way to Measure Incrementality


With the emphasis placed on measurement and proving ROI today, incrementality has become increasingly important to marketers who must prove whether their advertising campaigns caused a change in consumer behavior.

Marketers seeking to understand whether a campaign influenced a purchase (or additional purchases) or whether a certain group of people would have made a purchase anyway can leverage control groups to help answer these questions. This works because both the control group and the exposed group share the same behaviors and traits – the only difference being that one group was exposed to an ad, and one wasn’t.

Employing ghost bids and ghost ads is an emerging method for measuring incrementality, but it’s important to understand what they are, how they work and how they compare to other control group options. Below, read on for some answers to key questions about how to use these hauntingly named measurement tactics.

What do marketers need to know about leveraging ghost ads and ghost bids for incrementality?

Incrementality measurement can be provided with a clean, in-target, matched control group without additional costs associated with running the study, making ghost bids and ghost ads a cost-effective method of running a control group study.

How do ghost bids and ghost ads compare to other control group options?

There are multiple types of control group options available to marketers. As far as how ghost bids and ghost ads compare, they should be thought of as similar to a PSA Control (sometimes also called a Randomized Control Trial), but more cost effective. As a reminder, PSA Control groups are when Public Service Announcements are served within the same targeting footprint as an advertiser’s paid ad campaign. KPIs are compared against the two groups and incrementality is measured.

What’s the difference between ghost bids and ghost ads?

They’re similar, but it’s important to understand the slight differences.

Ghost bids are a control group made up of consumers who were within the campaign targeting criteria and active on the programmatic network, on whom a bid request was placed to show them the campaign ad, but the bid was lost. Those impressions are then passively tracked and included in your control group.

Ghost ads, conversely, are ads on which you purposefully lose a bid. As with ghost bids, they allow for accurate incrementality as your test and control are within the exact same targeting parameters. However, they do require runtime decision within the ad server in order to purposefully lose a bid you otherwise would have won.

What are the pros and cons of leveraging ghost bids or ghost ads?


  • Does not require additional funds to create a control group
  • Allows for maximum reach within the DSP (you do not miss out on reaching consumers within your target by using a holdout/intent-to-treat methodology)
  • Ability to measure all formats including CTV, mobile, and audio


  • There may be some limitations with small, niche audiences – think luxury buyers with incomes above $150k within a small DMA. This may be a harder group to reach, and competitors may be outbidding each other to reach the same audience, potentially impacting results.
  • Conversely, there may also be limitations with in-demand audiences, if others in the market are more successfully winning these impressions.

How is Adelphic’s offering unique?

Adelphic’s identity resolution capabilities in combination with ghost bid/ghost ad methodology allows marketers to evaluate omnichannel campaign effectiveness by ensuring that both the exposed and control groups are accurately defined and comparable.

Adelphic tracks the details on lost bids during a campaign and creates a control group. Both the control and exposed groups are mapped to the Viant Total Graph for identity resolution to confirm that the user was not exposed on another device. Results between the two groups are compared to provide incremental lift for KPIs such as sales, conversions, or visits.


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