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5 Impression Discrepancy Problems • Agency vs Publisher

5 Impression Discrepancy Problems • Agency vs Publisher

Wojtek Andrzejczak
Wojtek Andrzejczak
5 Impression Discrepancy Problems • Agency...

The discrepancy between delivered impressions is the most common any annoying campaign reporting problem. Let’s discuss this problem from the agency and publisher’s point of view because the solution to this problem is not straight forward.


  • The agency should use its platform reports to calculate campaign performance.
  • Total delivered impressions are the sum of the impressions + invalid impressions.
  • Google Campaign Manager is correcting data for up to 7 days.
  • Avoid discrepancies, check what tags publisher requires: Internal Redirect, INS.
  • The publisher counts impression before an agency ad impression.
  • The publisher should report more delivered impressions than the agency.

Agency vs Publisher

The difference in the campaign reports between the agency and the publisher is a common thing. But when differences jump to 20-60%, it becomes a severe problem. Base on which numbers should agency calculate campaign KPI’s which are reported to the client directly?

Agency needs reliable and repeatable reports so they could optimize their campaigns to achieve yearly goals for their clients. Depends on which campaign report we look at, we might receive significantly different results.

Publisher delivers what the agency has booked, using (in most cases) their ads. They report campaign performance base on reporting system their platform they use. Which very often is different from platform agency is using.

The Question

The publisher says that his delivery report is correct, and the agency that their report is correct. And both campaign reports show different impression delivery figures.

So who is wrong, and who is right?

The devil sits in the details. That’s why to answer the question. We need to go and discuss how the campaign setup and reporting system works from the agency and publisher side.

Before we start

In the described article, I mainly focus on the situation when the agency sends tags to the publisher. And the publisher sets them up on his platform.

A situation where the publisher is hosting creatives and agency sends the only impression & click tracking pixels are covered partially in this article.

Agency discrepancy problems

Let’s say our agency is using the Google Campaign Manager.

Imagine a situation when our campaign is over, and you would like to generate a performance report for your campaign. You think this should be easy and simple; how hard can it be?

Well, you are here, reading this article, so you can already assume it will be funny. And you are right.

Total delivered impressions problem

By default, we always talk about impressions and clicks in our campaign reports. But this is fine until you don’t receive a campaign report from the publisher, which does not use Google platform. Let’s assume our publisher is using AppNexus Xandr Invest.

In the publisher report, you see that they delivered more impressions about 15-35% and more clicks about 5-15%. And let’s assume that there were no other technical issues.

What you have received is a report for all physically delivered impressions, and clicks from the non-Google platform. So you need to generate a new campaign report but, with the Invalid Impression, and Invalid Clicks metrics.

Google splits campaign traffic, which might be generated by non-human traffic and human traffic. So to get total physically delivered impressions/clicks, you need to sum those metrics like this:

1. Total Delivered Impressions = Impressions + Invalid Impressions
2. Total Delivered Clicks = Clicks + Invalid Clicks

When you compare the campaign report again with the publisher, the discrepancy is not that significant anymore.

Google reports data corrections

As it sounds, Google Campaign Manager is correcting data over time. Sometimes it can happen that after 7 days, we’ll see different numbers for impressions, clicks, and conversions. Those differences should not be significant, but numbers still can change.

Publisher discrepancy problems

The situation with the Publishers is complex. Not only they are using different platforms, but also they deliver our ads to different websites, apps, and different formats.

Cross-platform reporting problems

Google platform is unique in the way how it counts impressions and clicks with invalid traffic. So when our publisher uses Google For Publishers platform, we’ll have the same numbers in the reports, right? Well, almost. Discrepancies should be up to 2%.

So the differences are inevitable; the perfect match is not possible.

In comparing reports, you must remember that each platform has:

  • the different methodology of how impression and click counts (Google CM)
  • differently implemented data aggregation mechanisms,
  • differently made ads preview and audit functionality, which generates impressions and clicks,
  • different reporting system,
  • the different post-event verification mechanisms.

Which tag should I use? INS tags? Internal Redirect?

The situation would be to easy if we had just a straightforward tag, but no, Google Campaign Manager gives us multiple options to deliver simple HTML 300×250 ad, and now what?

With Internal Redirect (IR), it is simple, and if our publisher is using Google For Publishers, we should always send them this IR tag.

It is crucial to send the correct type of tags to the publisher. Many times, I was investigating campaigns where impression discrepancies way over 20-60% in the reports because the Internal Redirect tag was not used.

If our publisher does not use Google For Publishers, then we send Google INS tag to use.

So it is simple like this? Unfortunately not.

The INS tags have 2 rendering modes Iframe and Script. The Iframe mode uses an iframe to load our ad. The Script mode does not use an iframe.

Which should you use is not that straight forward to answer. It depends if we deliver to the web, or in-app, and how/which SDK’s developers have implemented.

If you have significant discrepancies for INS Script tag, ask the publisher to make a test and to switch to the INS tag to the Iframe mode.

Ad tag delivery timing problem

Counting impressions in each advertising platform are defined differently.

By Google Campaign Manager, the impression counts when the first ad request has started downloading the content of our ad. So our ad is not yet delivered (displayed) to the user, and publisher impression is already counted.

The situation looks like this:

  1. The website has an ad slot, which displays an ad from our publisher.
  2. Publisher server delivers our ad, wrapped by his tag, so he could also count impressions, clicks, viewability.
  3. When the publisher tag is delivered to the website, his impression gets counted.
  4. At this moment, our ad starts loading because it was inside of the publisher tag.
  5. And then our impression gets counted.

Between those steps, it is enough time for the user to close the page, or go to the next page. Website speed also has a significant factor; when the website contains a tremendous amount of content, it takes a long time to load everything, ads are also part of the content here. The speed of mobile internet is also a significant factor.

Ad delivery drop off rate

I don’t think there is such a term, but I don’t know how to describe it in the other way.

Agency can not report delivered impressions because the ad is not physically delivered, so the user did not saw the ad.

I define delivery drop off rate as the percentage difference between impressions delivered by the publisher and impressions reported by the agency.

If we consider that the publisher delivered 1000 impressions and the agency can report only 893 of those impressions, then 10.7% of ads never had a chance to be seen by the users.

We can compare it to the situation when a video ad loads to the user, the video player is buffering the data stream, but the user closes the browser. The user never sees the first frame of it.

The Answer

Agencies should consider their campaign reports as those which describe the delivery of the performance of their ad.

Publisher reports should not represent agency campaign performance. Publisher does not know when the agency ad is physically loaded. Impressions, clicks, and viewability metrics describe not ads but advertising space performance.

I’ve described just a few most common problems. And many other factors have an impact on the discussed problem — but I try to focus only on the technical ones : – )

Helpful links

  • Contact Me
    Contact me if you need advice or if you need help. Would you please choose the most suitable contact channel for you?
  • My Services
    If you need a technical specialist to technical support to fix your problems, you are in the right place.
  • Who I am
    Hello, my name is Wojtek, I’m an experienced Software Engineer, with many many years of experience in the advertising industry.

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