Reduce Discrepancies Between Ad Manager and Google Analytics

Updated on: January 3, 2024
Learn how to reduce discrepancies between Google Ad Manager and Google Analytics data sources.

Have you recently integrated Google Ad Manager and Google Analytics, only to find discrepancies between the data sources when switching between reports? If so, you’re not alone. Many publishers have raised this question with us numerous times.

When comparing data, one major difference in reports is the metrics used in Google Ad Manager and Google Analytics. For example, reports that include total ad impressions, unfilled ad impressions, and fill rate in GAM may differ from pageviews and sessions in Google Analytics. Understanding these differences and reducing any discrepancies in the reports is important as it allows you to identify the true revenue potential of the website.

Before addressing the discrepancies, examining why the data points aren’t lining up is important. By closely examining the data sources and how they collect and report data, you can better understand the discrepancies and take steps to address them. With a clear understanding of the metrics and data collection process, you can ensure that your reports are accurate and reliable.

Reasons for Differences Between Ad Manager and Analytics

Different Pieces of JavaScript Code

When it comes to counting ad impressions and page views, there is often a discrepancy between Google Ad Manager and Google Analytics. Ad Manager counts an ad impression when the server responds to an ad request and serves the ad creative, while Google Analytics requires the user’s browser to execute its tracking code to count page views. 

This means that the two platforms load and execute separate JavaScript code on the website, and if the snippets are not loaded asynchronously, there can be problems.

For example, if a user enters and exits a page before the GAM code is loaded and executed completely, Ad Manager might not count the ad impression, but Analytics might still count the pageview. This can lead to inaccurate reports and significant discrepancies. 

To avoid these issues, it’s important to ensure that both snippets are loaded asynchronously and that Ad Manager and Google Analytics clearly understand the data collection process. By taking these steps, you can ensure that your reports are accurate and reliable.

What can you do? Ensure that both codes are placed at the same location and load asynchronously.

Usage of iFrames in Ad tags

We’ve seen changes in the ways publishers are using ad tags. Today, almost every publisher uses iframes or Safeframes to house the ad tags instead of CSS-defined ad units. 

Therefore, if a user is served an ad with <iframe> tag and the user’s browser doesn’t support the tag, then the Ad Manager will not count an ad impression. However, Google Analytics will count it as a pageview. As a result, there will be differences in the ad impressions served and pageviews.

Ad Blockers Installed on the User’s Browser

Ad blockers or firewall software installed on the user’s browsers are one of the major reasons why your stats are inaccurate. Adblocker plugins do not only block ads but the tracking codes too from loading on the websites. In this case, your GA code gets executed, but the server’s code doesn’t, and the reports you pull out may have different values.

What can you do? Identify the users who are using ad blockers in their browsers. Because adblockers will always cause some discrepancies, try these tips. They will help you recover the ad-block revenue and reduce the differences in the future.

Difference in Time Zone

You’ll see a difference in data when your Analytics account’s time zone doesn’t match the Ad Manager reporting time zone. For instance, if you are on the Beijing Standard Time, your Google Analytics account displays the time in UTC-8:00 while Ad Manager displays the time in IST-5:30. 

Since there is a discrepancy of a few hours between the two, you may sometimes see dates overlapped in the reports. Hence, inaccurate reports.

What can you do? Ensure the timezone is the same for both accounts. To change the timezone in Ad Manager, go to Google Ad Manager’s home page. Click on the More icon and Settings. Here you can change the timezone*. 

Note that the timezone can be changed by an administrator or an enabled user by the administrator. Similarly, for Google Analytics, click Admin. Go to the Property settings row. Here, you can find Reporting time zone to edit accordingly.

Analytics and Ad Manager Codes Aren’t Placed Correctly

A common source of error is when the Google Ad Manager code and Analytics code are not installed correctly on the page. For this reason, both codes must be installed properly on the same page of your website and in the right HTML locations. The next step is to ensure that the customized settings must be consistent across products (Google Ad Manager, Google Analytics, and Google Tag Manager) for your data to be accurate. 

For instance, if you’ve set up the website with a custom name ( in Google Analytics, the domain name should be the same in Ad Manager before the server sends the first GPT request to the demand channels.

What can you do? Ensure that both the codes are placed at the same location and double-check the details across all (GA, GAM, and GTM).

Clicks and Sessions Aren’t the Same

It’s known that Google Ad Manager counts clicks and ad impressions, while Google Analytics tracks sessions and pageviews. For example, if a user clicks on your ads thrice in 15 minutes without closing the browser, Google Analytics will consider it one session. But Ad Manager will count three clicks. So, do not confuse clicks with sessions in the two reports.

Ad Manager Filters Invalid Activities, While Analytics Includes All Data

Not everyone seems aware of this, but it’s an important difference to have on your radar. Google Analytics gives you full visibility on everything that happens on your website, while Google Ad Manager gives you a filtered view of your data (and doesn’t include invalid clicks in the reports). So, if there is a difference, it could be because of invalid activities on your website.

What can you do? To remove discrepancies between GAM and GA data reports, identify and remove the invalid activity from your website. This guide will help you in tackling the challenge.

Setting Up a Passback Method

Chances are high that you know what a passback method in Ad Manager is. But have you ever thought if it contributes to discrepancies in the reports? In passback, the ad server returns a third-party tag to the user’s page, and if the third party doesn’t have an ad creative to serve, the server makes another call to the next third party to deliver an ad on the website. 

If the third-party returns the ad, Ad Manager counts it as two ad impressions (the first impression when the server serves a third-party tag to the user’s page and the second when it actually serves an ad to the user). But Google Analytics will count it as one pageview.

What can you do? Refer to this guide to reduce impression discrepancy. This will help you even if you run header bidding and discover report discrepancies.

Wrapping Up

The mismatched data you see in your Ad Manager and Analytics accounts are usually considered normal. However, if they’re greater than 10%, you might want to investigate what’s going on. We’ve tried to include the most common and specific reasons for discrepancies. Some discrepancies have little to no impact on your revenue, while others can be huge – impacting the revenue significantly. So, if you find huge differences in the reports, make sure to resolve them ASAP.

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