How to Avoid Keyword Cannibalization Between PPC & SEO

What is keyword cannibalization in PPC and SEO?

Most brands will use pay-per-click (PPC) and search engine optimization (SEO) to acquire new customers. While SEO and PPC are often complementary, they can overlap, leading to the cannibalization of search terms or users. Suppose a brand is paying to acquire a user from the search engine results page where it is not incremental to their business as organic search would have acquired that user. In that case, it is defined as PPC cannibalizing SEO. 

This has become more common over recent years as PPC teams have moved away from targeting exact-match keywords to broad-match and automated campaign types, which offer less control over where they show. 

Identifying signs that you are cannibalizing

To identify areas of cannibalization, brands will typically look for paid search queries they are bidding on, where they rank p1 in the organic result, and there is no competition. The overwhelming majority of these cases are their own branded terms. 

Identifying instances of cannibalization in this way can be difficult for several reasons:

• The number of ads can vary from query to query in the search results, making it hard to know when ads are really showing. Auction Insights reports within Google Ads provide very limited data in this regard.
• There is no keyword-level data in Google Analytics, which makes it difficult to see the specific details of where PPC queries are cannibalizing organic traffic. Keyword data is available in Google Search Console but does not include conversions. 
• As mentioned campaigns such as Dynamic Search Ads and PerformanceMax target keywords without the user setting them. This means PPC advertising might appear to be unknowingly against specific terms. This is one of many reasons PPC teams need to be constantly creating a search term report to monitor where their ads appear

For these reasons, creating a structured plan to understand and address areas where PPC may be cannibalizing your SEO efforts is essential. 

Avoiding Keyword Cannibalization in PPC

Steps to avoid  PPC keyword cannibalization 

We have created a process to prevent cannibalization that should be adopted within your SEO & PPC campaigns.  

Unified keyword research

The reason for cannibalization is when both channels target the same keyword. This often occurs when teams do not communicate with one another. We suggest that keyword research becomes a joint piece of work between departments, with teams sharing lists of keywords that include:

• Common categorisation (using a keyword research tool such as Keywordinsights.ai makes this very simple)
• Search volume (again taken from a keyword research tool)
• SEO and PPC data, such as historical conversion rates and difficulty per channel (taken from Google Analytics and Google ads)

This list should be used to prioritise target terms within the SERP for both paid and organic, creating an easy way to identify keywords overlap. Both teams can create joint keyword strategies, perhaps focusing PPC on areas where SEO underperforms. 

Using analytics to monitor the performance of PPC and SEO campaigns

Due to SEO keyword restrictions outlined earlier, there is no simple way to monitor for keyword cannibalization issues within Google Analytics. If you have resources available, it is possible to use BigQuery and Google Looker Studio to produce combined reports or even tools like Supermetrics. If not, Google Sheets can be used to enter data manually. We'd normally create reports that show:

• Visits for both paid and organic search campaigns at a keyword level (taken from Google Ads for paid and Google Search Console for organic)
• Conversions at a keyword level for paid 
• Conversions at a landing paid level for organic
• Combined click-through rate (CTR) of both channels. We'd use impressions from Google Search Console. 

Combining this data at a keyword or keyword group level will give your teams a quick way to investigate potential areas of keyword cannibalization in their day-to-day reporting. As mentioned earlier, it's essential to understand where automation within your Google Ads account is causing ads to show by regularly reviewing the search term report. 

Creating a structured testing plan

The ultimate form of understanding cannibalization between paid and organic is incrementality testing. This tells you how many incremental conversions your ad campaign drives or what would have happened if you weren't running ads. 

It is possible to conduct this type of study in Google Ads , called conversion lift studies, with the aid of a rep. This splits ad delivery into two groups: one who sees the ads and one who would have seen the ad but doesn't and sees whatever the following ad in the auction is (or no ad if there wasn't another one). At the end of the study, Google will compare the results for both groups to calculate how many of the conversions were driven by the ad being shown vs. those that would have occurred anyway.

Outside of Google running the incremental test themselves, brands can run a hold-out test to understand whether PPC cannibalises SEO. This requires brands to effectively turn off ads for a defined period and compare that to a previous period to determine whether the paid search ads added incremental conversions or were taking those SEO would have collected anyway. To do this, we recommend:

• Picking a period with minimal noise. If you are doing a comparison, it should be outside periods like sales or heightened interest caused by advertising. Ideally, the conditions for the comparison period should be as close as possible.
• Running a keyword report from Google Search Console and comparing the number of impressions captured by organic vs those captured by paid and organic combined when ads were live. This way, you can ascertain whether clicks are being lost by not spending on PPC

Utilizing negative keywords in PPC campaigns

Once you know where PPC ads compete with organic results in a non-incremental way, you can fix keyword cannibalization. The quickest way to do this is to apply negative keywords to your Google ads campaign to stop PPC from appearing for non-incremental keywords. The drawback is that while this stops SEO and PPC from targeting the same query, it isn't reactive. If a competitor starts bidding, it may not be until you identify a decline in organic click-through rate that you realise there is an issue and are losing conversions. This makes it unfeasible for your PPC team to manage on any large scale. 

Balancing PPC and SEO strategies for better results

Once a cannibalization strategy is in place, there are other ways SEO and PPC campaigns can work together. These include:

• Complimentary PPC and SEO messaging to maximise click-through rate 
• Using paid search campaigns to inform SEO targeting 

In summary

Cannibalization occurs when PPC and SEO target the same keywords, and it harms your business as you are paying for conversions you would have got anyway via organic. Common signs that you are cannibalizing organic is bidding on terms with almost no competition, where you rank number one in organic, typically on brand terms. 

Diagnosing cannibalization at scale is challenging. Joint keyword targeting and reporting and a series of structured tests are steps to avoid it.

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