Understanding how Performance Max (PMax) and Search work together can be challenging. Is PMax cannibalizing Search ads? Google Ads doesn’t make auditing PMax search term data easy, requiring extensive downloading and spreadsheet analysis to identify meaningful trends.
That’s where our research at Adalysis comes in. Through our PPC management platform, we have access to unique datasets and possess the technical expertise for analysis at scale.
This study focuses on non-retail PMax only, based on data from over 3,300 non-retail PMax campaigns containing around 1.2 million search terms. A future study will focus on retail PMax for similar purposes.
We’ll investigate:
This study will show if Google prioritizes one campaign type and how extensive the overlap is. We’ll also discuss how to use these insights to optimize your account’s performance.
To avoid skewed results, we excluded PMax search terms with fewer than 10 impressions.
Google’s documentation references how search terms should trigger ads from Search and PMax campaigns. Understanding the intended priority order helps put our research into context.
In this help file, Google sets out how PMax works with Search campaigns:
So far, this is straightforward and implies that for all search terms that are identical to keywords of any match type, your Search ad should show. For all other search terms, Google will use the campaign with the highest Ad Rank of any eligible keywords and PMax asset groups.
However, we’ve found another help file that states:
This implies:
(As a reminder, search themes in PMax campaigns can match any related search terms.)
This isn’t quite the same message. With this in mind, we decided to test what happens in real-world scenarios.
We aimed to determine how often PMax ads were displayed for search terms that already existed as keywords (of any match type) in Search. This only occurred 2.8% of the time across all PMax campaigns, with many accounts showing zero overlap. (These accounts often had a small PMax campaign and very few Search keywords.)
A 2.8% overlap at the search term level is minimal. However, at the campaign level, 67% of PMax campaigns had some overlap with Search campaigns for one or more search terms.
There was also a wide range of overlap. Some PMax campaigns had zero overlap, while others reached 100%. For campaigns with 100% overlap, every PMax search term was also a Search keyword.
One interesting observation we made was that many PMax search terms contained misspellings and missing spaces (e.g., “papajohns” instead of “Papa Johns”). Google has consistently stated that you don’t need to add misspellings as keywords, but this presents new implications for running concurrent PMax and Search campaigns. If misspellings aren’t added as keywords, a misspelled search term won’t match your correctly spelled keywords. That might allow PMax ads to be shown instead of Search ads.
Google also no longer reports on misspellings for search terms in your Search campaigns. As a result, it’s impossible to analyze the impact of misspellings on Search and PMax ad serving. This was confirmed in a LinkedIn update by Ginny Marvin from Google.
In summary, since 67% of PMax campaigns have search terms that overlap with Search keywords, we recommend reviewing the overlap in your own accounts, as it can range anywhere from zero to 100%.
You can easily view and analyze this data in Adalysis, which we’ll cover later in this article.
Next, we explored how often search terms triggered both Search and PMax ads i.e. the same search term exists in both a Search campaign and a PMax campaign. We found this overlap rate to be 45%, indicating that almost half of PMax search terms can show ads from either Search or PMax campaigns.
It’s important to note that Search ad groups usually consist of tightly themed keywords and ads. The ad copy will likely be highly relevant to the search term.
In contrast, PMax involves creating ad assets to cover a large variety of search themes. Consequently, most advertisers consider their PMax campaigns to be less relevant than their Search campaigns for the same search terms.
This discrepancy can result in dramatically different user experiences for the same search term. Some users may see a PMax ad, while others may see a Search ad. Repeated searches can yield ads from different campaigns.
To better understand how Google prioritizes which campaign type to render the ad from, we looked at how the impressions of the same search term compare between the campaign types (for the same date range). Our data shows that PMax ads had more impressions 43% of the time.
As previously noted, some accounts have no overlap issues — Search and PMax match separate search terms. When we excluded those campaigns from our analysis, PMax achieved more impressions 61% of the time.
Since we’re ignoring all search terms with less than 10 impressions to avoid skewing the CTR and conversion rate data, the overlap rates are actually higher since this data only includes terms with at least 10 impressions. However, this data will give you an idea of how often overlaps occur for higher-volume search terms.
This raises an important question. Consider a search term that matches a phrase or broad-match keyword and a search theme. In this case, Google performs an Ad Rank calculation and prioritizes the targeting method with the highest Ad Rank.
Given that PMax has more impressions than Search 61% of the time when there is overlap, this may suggest that PMax holds a higher Ad Rank than Search.
Expected CTR is a quality score component that is a factor in the ad rank formula. While Google stores auction Quality Scores at the search term level, we can make inferences about which campaign type could have higher Quality Scores if one campaign type has a significantly higher CTR than another campaign type. The difference in CTR could explain why PMax outperforms Search for total impressions.
For overlapping search terms, Search achieved higher CTRs 65% of the time. This makes sense. PMax assets cover a broad range of search themes and terms, while Search ads are usually written for specific keywords.
However, this finding doesn’t explain why PMax has more impressions. Many advertisers apply conversion based bid strategies. If a campaign type has a higher conversion rate than another campaign type, then a higher bid would be submitted to the auction for the higher conversion rate campaign type.
The bid is a large component of Ad Rank. Ad Rank is one of the factors that determines which campaign type will show for a search term. We would expect the higher conversion rate campaign to have more impressions for the same search terms than the lower conversion rate campaign.
While Google determines bids at the search term level, we’re looking for overall trends by comparing campaign conversion rates by campaign type to understand why PMax shows more often than Search campaigns for the same search terms.
Search campaigns had higher conversion rates for overlapping search terms 84.18% of the time.
Google does not publish cost data for PMax search terms, so we can’t calculate the difference in ROAS between Search and PMax campaigns. However, we know that PMax gets more impressions than search, so we would expect PMax to have higher conversion values. In reality, Search had higher conversion values 84.62% of the time.
This means with fewer impressions, Search campaigns drive more revenue than PMax campaigns.
This data shows that PMax doesn’t have more impressions because it performs better. If you’re running PMax campaigns for lead generation, you’ll want your top search terms to show Search ads. This will likely lead to higher CTRs, conversion rates, and conversion values.
Since Search usually outperforms PMax for the same search terms, optimizing the visibility of your Search campaigns can lead to higher conversion rates and return on investment (ROI). We recommend carefully managing your search terms and adding exact match keywords where relevant.
In Google Ads, you can access your PMax search term data by clicking on a campaign and then navigating to ‘insights and reports.’
Scroll down to the search terms insight section, click ‘view detailed data,’ and download it. Please note: The download speed is significantly slower for PMax search terms than for Search campaign search terms. You will also need to repeat these steps for each PMax campaign.
Once you have your data, review your top PMax search terms to see if they are already Search keywords. If they aren’t, add them as exact match keywords. Ensure every Search ad group uses relevant ad copy and landing pages, as this should increase CTRs and conversion rates for those terms.
Alternatively, you can view and manage this data using the PMax search terms feature in Adalysis. (We offer a 30-day free trial.)
Adalysis will show you:
You can also get more detailed data on the performance of those search terms for search and shopping campaigns, so you can always make an informed decision.
You may see a Google Ads recommendation to ‘remove redundant keywords’ when adding search terms as keywords. Keep in mind that if you accept that recommendation, you will not have the identical keyword in your search campaigns, which means PMax can trump search for those search terms. This is one reason we recommend ignoring this suggestion.
To optimize your Search campaigns, monitor your search terms closely and add your top search terms as exact match keywords. This simple step will help you prioritize Search campaigns over PMax campaigns.
PMax can provide excellent value, especially for e-commerce. For lead generation, it often functions as a cross-channel backfill, serving ads across the display network, apps, and remarketing.
Another approach is to pause PMax and focus on expanding your Search and Display campaigns using the data you’ve gathered. Several large advertisers have adopted this strategy in recent months.
We hope you’ve found this analysis helpful. Please share it with your network and let us know how you use PMax for lead gen.
Next up: the impact of lost PMax impression share data. Subscribe to our blog, and we’ll send you the article as soon as it’s published.
