Overview

Ghost Bidding is a testing framework designed to measure the incremental impact of media buys without incurring the cost of control group impressions. Within this framework, certain bids are excluded from the auction and designated as "ghost bids." These ghost bids do not win the auction, but they are still tracked for testing purposes. Beeswax predicts whether these ghost bids would have won the auction if they had been included. If the system forecasts that a ghost bid would have won, it generates a corresponding "ghost impression." These ghost Impressions effectively create a control group consisting of users who are treated as though they had been exposed to the ad, even though they did not actually see it.

Using this control group, Beeswax compares the conversion rates of users who saw the ad with those who did not. This allows for an analysis of the incremental lift, which reveals how much of the observed conversion behavior can be attributed to the ad exposure itself, as opposed to other factors. The results of this analysis are available in the Incrementality Report, which can be accessed through Reporting. For those interested in more granular control, ghost logs are also available. These logs provide transparency into the ghost bidding process, offering detailed data for those who wish to experiment with or refine elements of the methodology.

How Ghost Bidding Works

Treatment and Control Group Assignments

• Ghost bidding assigns 80% of users in the treatment group (real bids) and 20% of users in the control group (ghost bids).
  
  
• Bid requests get assigned a user index (1 to 1000) using a hash based on the User ID type. User index 1 to 200 = control group and 201 to 1000 = treatment group.
  
  
• Beeswax uses Standard or IP Address for identifying ghost bidding User ID Type.
  
  
  • For Standard Ghost Bidding User ID Type, Beeswax uses cookies.
    
    

  • For the IP Address Ghost Bidding User ID Type, Beeswax uses both IPv4 (IP version 4) and IPv6 (IP version 6). However, if both types of IP addresses are present in a bid request, IPv6 will take priority over IPv4.

    Additionally, if a bid request contains obfuscated IP addresses (where the IP is hidden or masked), that request will not be eligible for line items using IP Address as the Ghost Bidding User ID Type. In other words, only bid requests with visible, non-obfuscated IP addresses can be used for Ghost Bidding based on IP address.

Ghost Bidding

• All requests go through targeting, creative matching, pacing, and frequency capping to see if a line item bids on it.
  
  
• If a line item bids and the user has been assigned a user index between 1 to 200, then the bid will be dropped (not sent to the exchange) and logged as a ghost bid. 

Win Prediction

• Beeswax predicts whether a ghost bid will win and become a ghost impression. To make these predictions, Beeswax trains win rate models daily for each line item on the previous day's data. For the model to perform well, it needs sufficient data. Specifically, the model requires at least 5,000 impressions from the previous day to be effectively trained.
  
  

• The Beeswax model training process runs daily, therefore, ghost bid logging will begin only after the model has been trained and deployed for the line item. Ghost bid logs are typically viewable the day after enabling the feature.
  
  

Treatment vs Control Group Conversion Attribution

• When Beeswax receives a conversion event, it runs attribution methodology across both treatment (real) and control (ghost) groups impressions to determine which group was responsible for driving a conversion.

  This is not supported for in-app/postback/SKAd attribution methods because these attribution processes are run outside of Beeswax.

Activate Ghost Bidding on a Line Item

Ghost bidding is enabled at the line item level and can be configured during the creation, or when editing the line item. Please follow these steps to understand how ghost bidding is applied:

1. Navigate to a line item's General screen (either during or after creation of the line item).
   
   
2. Scroll down to the Ghost Bidding section and expand it.
   
   
3. Set the Enable Ghost Bidding toggle to 'YES,' then choose the appropriate Ghost Bidding User ID Type—either Standard or IP Address—which will be used to categorize users. See below for more details on each ID type.
   
   
4. Click Save.

Ghost Bidding ID Types

Ghost bidding can be configured to use one of the two different ID types:

ID Type	Description	Supported Conversion Types for Incrementality Report
Standard	Cookie for Web MAID for Apps Connected TV ID for CTV	Non-Postback
IP Address	IP Address	Non-Postback

Reporting & Logs

Incrementality Report

In reporting, the Incrementality Report  calculates the incremental lift and other key metrics across both treatment and control groups, including impressions, conversion, conversion value, and conversion rate. Incremental Lift is calculated using the following equation: (Treatment group conversion rate – Control group conversion rate) / Control group conversion rate.

Ghost Logs

Beeswax offers ghost win logs for users who would like to run their own attribution methods, and ghost attribution logs for users to run their own incrementality analysis. Please speak to your Beeswax Account Representative to enable ghost logs.