Prebid Webinar Key Takeaways – How to make Prebid the supply path buyers choose

Posted by Asmaa Bentahar on

Disclaimer: This a summary of the Prebid Webinar that took place on August 27th 2020.

Update on

The community keeps growing with now up to 64 members while the number of engineering contributions and releases keeps increasing. Prebid area of focus is broadening with several new major updates in the Identity module and the creation of two new working groups.

The Taxonomy & Standards new working group aims at defining standard log file formats and interfaces across the industry to be able to share log files for transparency purposes and reach a true end to end interoperability. This should also help publishers identify categories and create audience segments. Prebid will work alongside the IAB tech lab who has a similar offer in place.

The CTV/OTT new working group will focus on long form video content and television. It is different from the existing Video task force currently focused on in page video and outstream.

Identity module and Privacy sandbox

Prebid has taken full ownership of the PubCommonID identifier. It is now owned by the community, for the community !

The identity module now contains 12+ identifiers among which Publishers can choose the most relevant ones for them. As a reminder the identity module architecture makes it very easy to add new identifiers in a standardized way and write them both as first and third party.

In addition, Prebid is involved in the W3C Privacy Sandbox and will act as an intermediary to keep the community up-to-date without going too much into technical complexity. Some of the proposed framework will be implemented within Prebid for testing purposes.

Key features in the work

“Min Bid to Win” notification to share clearing price information to buyers. More and more actors are willing to share auction information in an open and transparent way.

A forecast feature, to properly determine the amount of inventory available and share this information with buyers and publishers.

Enhancing the identity module to support SSO models like The Trade Desk initiative.

The Intelligent Price Floor open architecture is ready and available. Publishers or tech actors can build data packages to send dynamically in the wrapper during the auction. Prebid is moving towards a dynamic management of the wrapper and encourages everybody to try and build on these new features !

Publisher best practices by the Publisher Taskforce

Stay on top of the tech ! You may for instance consider trying Prebid Server to go beyond browser limitation and improve the latency of your wrapper and pages. Try and experiment with Prebid flooring module and push for your SSP partners to support it. Last but not least you should install an analytics provider to better explore your advertising metrics, find some hidden issues and optimize your stack.

Make sure you have a proper implementation of your front end code: for instance don’t run Prebid auctions on non programmatic eligible adunits. Also make sure your code is optimized and loads all the relevant resources and scripts in the appropriate order and with the right logic.

Use and abuse of A/B testing, this is where you can learn and experiment. However don’t focus only on CPM, you should also look at user experience metrics such as session length, bounce rate, page views per session, page loading time. A popular practice is to A/B test each bidder value individually and not just assume more competition will lead to higher revenue. Common experiments also include A/B testing timeout on different devices, websites and browsers.

When integrating Prebid with your ad server make sure to create line items with granular CPM, especially where your bid density is high. For instance consider using 0.01$ increment. In addition you should often check bidder discrepancies and use discounts to prioritize those who pay on a lower net term or in time. Eventually think about implementing some alerting to know as soon as possible when a drop of revenue occurs on your websites.


Q – What is an efficient Supply Path Optimization ?

A – We can take into account the financial distance (overall fees on the supply path) and the technical distance (complexity of the supply path). The win rate of a supply path is catching both information and could be used as a supply path efficiency metric.

Q – What is an acceptable win rate ?

A – It varies a lot, mostly when publishers are doing a lot of direct sales. However you can set-up an experiment with very high bids to find a “target win rate” and measure the delta with all other programmatic channels to assess the efficiency of each of them.

Q – What’s your take on resellers ?

A – For a buyer, resellers are often cheap but before working with them you should always make sure they provide full transparency on their business model and inventory source.

A – As a publisher you always wanna make sure to keep control on your flooring strategy and on the practice of these actors.

Q – Is there any long terme hope for Video knowing the latency and VAST issue ?

A – From a publisher point of view, implementing Prebid Video helped us increase our revenue but it required a lot of custom code and implementation.

A – VAST format was not designed to support unified auction and there is still some work to be done in collaboration with Prebid to optimize video efficiency. Yes, there is long term hope !

Q – How does Prebid plan to bring Intelligent Floor out of GAM ?

A – Mature publishers like Cafe Media have their data science team on the floor topic. It is likely soon some products will also be developed by third parties.

A – Taking this in GAM or other Ad Servers takes time and requires more collaboration with Google. Some small “hack” exists to pass the floor information to GAM through some key-value but it can be costly to maintain.

Q – Any advice on match rate issues when moving from Prebid.js to Prebid Server ?

A – There is evidence on the market it is possible to achieve a high match rate on the server side so this issue seems fixable.

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