What is it?
The process by which the ad-server (Steve) increases or decreases the count of real-time (RT) impressions delivered each day to bring them in line with the delivered IAB valid impressions.
Why do we do this?
Since the introduction of BERTi (“Better Effort Real Time Impressions”), this results in having, in the vast majority of cases, less RT impressions than IAB valid impressions.
What this means is that Steve, when pacing a flight towards its Booked Impressions goal, it can lead to delivering more impressions than the goal (over delivery). This happens because while the IAB impressions are used for setting the goal and for billing, RT impressions are used by Steve for pacing purposes.
So Steve, believing it still has more impressions to serve to reach the goal, continues to do so until the RT impressions reaches the goal number.
On average, BERTi produces a difference from RT to IAB of around -1.5% - meaning without a reset/synchronization of the two numbers, all flights, where the goal is achievable, would over delivery by around 1.5%.
The reset is in place so that, each night when we get the IAB number, we increase the RT number to match the IAB so that the -1.5% difference is removed; resulting in us being much closer to hitting 100% of the goal vs 101.5%.
How does it work?
Every 24 hours we get the previous days IAB valid impressions. This occurs and is processed mostly between 2am-5am UTC.
At this time when we receive the IAB, we take the difference between the two numbers and sync them.
The process itself can take some time, during which we can be accruing RT impressions. We of course account for these. So once the sync is completed, any accrued RT impressions are also added back on top - this means that we have a 0% discrepancy plus any impressions occurring during the sync window. This is why in the UI you would never see a 100% match between the two numbers, but to Steve, they are aligned and pacing is being performed more accurately to the Booked Impressions goal.
The reset is applicable:
When the flight is NOT billed against 3rd party impressions
The flight has an impression goal (not unlimited)
For all ad types
The reset occurs every night aside from the last 48 hours of a flight. This is to ensure that, where the discrepancy might be very close to 0%, if on any of the last 2 days, if the discrepancy between RT and IAB for the previous day was positive (i.e. more RT than IAB), if we reset and equalise up until the last day, if we get more RT on the final day of the flight than IAB, this can lead to an under delivery of the flight overall.
How is this configured?
Via Ad Manager, on the Flight config you have a toggle to enable or disable.
Reset will be enabled by default upon the creation of a flight unless the flight is billed against 3rd party impressions or has no impression goal.
It can be disabled and enabled at any time - but the best practice would be to have the reset enabled in all circumstances.
Should I still use buffers?
Buffers should become redundant with the use of the reset.
The reset is designed to bring the pacing of a flight inline with the IAB booked impression goal. Buffers are generally used to force the ad server to push to deliver more impressions to counteract a discrepancy which would lead to under delivery.
In the case of the reset, it is essentially automating this process.
Buffers can still be used if there are cases where you wish to deliver more impressions than the goal (e.g. Spons with added value), but otherwise, they should not be required if attempting to cover for the discrepancy between RT and IAB.