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When Should You Delete a Low Traffic Keyword?

Regularly researching keyword opportunities and expanding your term list is critical to the success of a paid search program, but knowing when to delete keywords with low potential is also an important consideration in managing PPC accounts at scale.

Why Delete Keywords at All?

In addition to the engines having finite account size limits, keyword lists, especially in large, mature accounts, can grow to an unwieldy size as new keywords are added throughout the years.  This can make it more difficult to quickly enact time-sensitive changes such as promotional copy additions and intraday bid adjustments.  Thousands of additional keywords translate into hundreds of additional adgroups and internet and search engine API bandwidth limitations restrict how quickly requests can be transmitted and processed.  This issue is compounded if keywords need to be duplicated in various parts of the account for testing or geotargeting purposes.

Also, while you may not see much in direct costs associated with allowing keywords that aren’t generating many clicks to continue running in the account, these no click/low click-through rate keywords may be lowering your Account Quality Score and indirectly raising the costs per click of other keywords in the account.

Perhaps worse than not pruning low impression/traffic keywords at all, paid search account managers may arbitrarily decide to delete keywords that have not had an impression or click within a time-period of X, where X is a nice round number like 30 days, 6 months, or a year.  We hope our analysis below will help account managers make a more data-informed decision, minimizing the negative impact this task could have on long-term sales.

Before We Begin…

  • We assume keywords without impressions, clicks, and/or orders have been appropriately optimized (ex. for low/no impression keywords).
  • The data analyzed in this post categorized a single keyword with separate matchtypes and campaign settings (ex. location, language, networks, device, etc.) as separate, individual data points.
  • RKG, while balancing financial risk and rapid learning, tends to set fairly aggressive initial bids, so the windows between a keyword’s early impressions and clicks may be biased a bit shorter compared to more recent data, but the early data is still a reasonable proxy for future performance patterns.  We are using the earliest data here in order to incorporate sales and cost figures generated over the full lifetime of the keywords.

Deleting Keywords Without an Impression in X Days

For this part of the analysis, we aggregated the lifetime sales and costs of non-brand keywords from a bucket of well-established accounts (average age of 4 years) by the time between each keyword’s first and second impression.

The following graph shows the relationship between that time difference and a keyword’s lifetime contribution as a percentage of total account sales and costs.On average we found an account would lose about 1.0% of long-term sales and save 1.1% of long-term costs if keywords that did not have a second impression within 17 days of its first were deleted.

To be clear though, unless there are compelling reasons, we do not recommend deleting zero or low impression keywords before they have run for 365 days.  A full year helps to account for seasonality, even for the most specific keywords. It is not difficult to imagine a keyword such as “[Small Town] Valentine’s Day chocolates” launched on exact match in March not receiving any impressions until the following January or February.

For the very conservative account manager, 99.99% of total account sales and costs will typically be generated by keywords with less than two years between impressions.  If you have terms that fit that bill, you should be pretty safe to free up that account space.

Deleting Keywords Without a Click in X Days

Using a similar approach to identify keywords with no clicks or low click-thru-rates worth deleting, we aggregated the lifetime sales and costs of non-brand keywords from the same accounts by the time between their first impression and first click. The following graph shows the relationship between that time difference and a keyword’s lifetime contribution as a percentage of total account sales and costs.

This data shows that one would lose about 1.0% of long-term sales and save 1.1% of long-term costs if keywords that did not have a click within 150 days (5 months) of their first impression were deleted.

However, the data also shows that it took keywords with about 2.5 years between first impression and first click to generate 99.99% of total account sales and costs, which was longer than the age of a few of the accounts in our group.

Looking at the accounts individually, we found some had 99.99% of their sales/costs generated by keywords with less than 6 months between first click and first impression while it took other accounts’ keywords almost three years between first click and first impression to reach that 99.99% mark.

Age of the Account Impact

We quickly realized that the predominant factor for this variability was the age of the account. While the data for a head-heavy client in the early days looked very different than an account that benefited more from the tail, we saw a convergence of 99% of total account sales being generated by keywords that have had a click since their first impression at about 11% of the age of the account.

We see a similar trend as our previous graph, but on a more representative scale.

For the very conservative account manager, 99.99% of long-term account sales and costs will typically be generated by keywords with less than 70% of the account age between first impression and first click.

Summary

Remember that the information in this table is just a guideline based on the analysis of a subset of our client base. There is no substitute for a competent account manager that can identify the individual keywords that are increasing account management overhead, decreasing account QS, and otherwise adding only minimal value to the program.

Special thanks to Mark Ballard for his contributions to this post.

  • Kearby Chen
    Kearby Chen is a Marketing Strategy Director at RKG.
  • Comments
    21 Responses to “When Should You Delete a Low Traffic Keyword?”
    1. Mark Kennedy says:

      Very well done, Kearby (and Mark Ballard). When I go through PPC accounts for keyword pruning, I tend to use long periods of time to make my assessment, so I would fall somewhere between conservative and moderate. Usually a year minimum, but in some cases longer. Thanks for showing some hardcore data to illustrate your points.

    2. Martin Roettgerding says:

      Very nice analysis, thanks for sharing that data.

    3. Vegar says:

      I like to keep my keywords as long as the keyword make sense to the business.

      However if the keyword is getting 50 -100 searches each month and low ctr I would have to delete it or move it to a different adgroup.

    4. Kearby Chen Kearby Chen says:

      Thanks for the comments, Mark and Martin! We strive to support our best practices by analyzing the hard data and finding actionable results.

    5. Kearby Chen Kearby Chen says:

      Hey Vegar, we definitely recommend trying to optimize no impression/click/order and low CTR/CR KWs to give them a chance to perform before deleting them. Also, don’t forget to look at conversions too, a low impression and low CTR KW with conversions will have a high CR and is most likely worth keeping. Thanks for the comment!

    6. A. Meyer says:

      Thanks for sharing this, it’s a very interesting topic. I still have some open questions:

      - If I get you right, in case A (Deleting Keywords Without an Impression) you tell us about the impact of deleting keywords with more than 2 impressions in one year and more than 17 days between first and second click (=> the account would lose about 1.0% of long-term sales and save 1.1% of long-term costs). What would be the impact of deleting keywords with no impressions at all?

      - It is an interesting finding that the factor Sales:Costs is identical in case A and B (10:11). I would have guessed that it would be lower in case B, as these keywords should typically have a higher CPC (due to low quality factor of keywords with low CTR (B) & little competition on keywords without impressions(A) ). Is the conversion rate in case B higher and compensates high CPCs?

      - Did you observe a significant increase in the remaining keywords’ quality factor in case B (Deleting Keywords Without a Click)? That would be really interesting.

      - Finally, I do not understand this 99.99% thing. Do you really mean that there are accounts where 99.99% of the account traffic comes from keywords that had very low CTR in the beginning (2.5 years between first impression and first click)??? Or do I get it completely wrong?

    7. Kearby Chen Kearby Chen says:

      Hi Andreas, while we recommending optimizing keywords with no impressions and letting them run for at least a full year, deleting them would have little to no impact on their lifetime contribution to total sales/costs since they will not have generated a click.

      In addition, we found that keywords that take longer to receive their first click compared to their first impression also tend to be lower traffic, longer-tailed keywords that convert fairly well, balancing out their slightly higher CPCs with slightly higher sales. The fact that the sales to cost ratio between “Case A” and “Case B” were identical is simply a coincidence.

      The 99.99%, 99.9%, and 99% marks were indicators we chose to show how aggressive or conservative an account manager might want to be when deciding how many keywords to delete. In “Case B,” we found that 99.99% of sales/costs were generated by all keywords with less than 2.5 years between first click and first impression, i.e. the keywords in the account with the highest CTR. (Note that using % of account age instead of years is a better indicator of which of these higher traffic/CTR keywords significantly contribution to total account sales/costs).

      We did not look at individual keyword QS’s to see if they changed as a result of these deletions since we were taking a macro look across multiple clients. Also, since account quality score is based on the historical performance of your account, it may take some time before any positive impact is noticeable, however, if you see any quality score improvements with your account by following these recommendations, please feel free to post your results here!

    8. Great analysis Kearby.

      I rarely tend to delete keywords which have received any impressions, as I believe doing so conflicts with long-tail theory. For accounts where over 50,000 keywords have received impressions, I prefer to instead create multiple accounts. Although that said, obviously there needs to be a metric in place which trims keywords with NO impressions.

    9. Kearby Chen Kearby Chen says:

      Thanks for the comment, Alan!

      Also, don’t forget to try to request expanded limits for AdWords accounts; being able to manage up to 1M KWs in one account instead of multiple accounts should help significantly reduce management overhead!

    10. Paul says:

      Kearby — fantastic post. Really compelling stuff. I want to clarify something you mentioned early on, about how ‘no click/low click-through rate keywords may be lowering your Account Quality Score.’

      In saying this, are you making any distinction between Active vs Paused keywords? A lot of times, we’ll load up keyword lists with way more than we necessarily intend to run. It might make sense to trim the excess keywords, except that if we ever needed them again in the future, we’d have to do all the legwork over again, or identifying them and bucketing them in the right campaigns/AGs. So more often than not, we’ll just throw them on pause and leave them alone.

      This too might have an impact on account level quality score, you’re saying?

    11. Kearby Chen Kearby Chen says:

      Hey Paul, I believe “account quality score” is calculated using historical performance data (from Active keywords). Paused keywords that have never been Active should have a neutral effect so you should be fine!

    12. Igor says:

      Interesting topic. Would love to see what the analysis looks like when you think about deleting keywords with impressions & spend, but no CONVERSIONS over X days.

      I’ve seen lots of AdWords accounts where more than 95% of the keywords have never yielded a conversion, but clients will hang onto them for coverage and impression share.

    13. Scott Walker says:

      Great article! This report shows a great deal of technical expertise.

      From what I gathered, you are asserting that deleting keywords that have a long space between clicks or a long space between impressions will lower costs by 1.1%, while only lowering sales by 1.0% (for an aggressive Account Manager).

      Deleting these keywords would increase ROI for the overall account by 0.001% (0.990)/(0.989) by sacrificing 1% of sales volume. This does not seem like a fair trade. Am I confused about what each of these numbers mean?

      Thanks,

      Scott

    14. Kearby Chen Kearby Chen says:

      Thanks for the comment, Igor!

      In an ideal world, a good bid management system should bid down (or pause) keywords without conversions until they are no longer receiving clicks, enabling them to be deleted under our aforementioned guidelines regarding time between clicks. However, in the “real world,” a number of changing factors in the competitive landscape might cause a keyword to receive a click every couple months or so, thus resetting its “countdown.”

      It would indeed be interesting to take a look at keywords without conversions over X days and normalizing it by an advertiser’s click-to-order lag time. There may be an additional follow-up post addressing this; check back later!

    15. Kearby Chen Kearby Chen says:

      Hey Scott, you’re right that one would be sacrificing sales but you’re also increasing the ROI of the account by 0.1% (.99/.989 * 100 = 0.1%). That in itself is not necessarily significant, however, the benefits we mention previously of reducing management overhead, increasing account quality score, etc. should help indirectly save additional costs, thus boosting the overall magnitude of this ROI lift.

    16. Scott Walker says:

      Kearby, thank you for correcting my math :). You’re definitely right, increasing the overall account quality score would also improve ROI. Just for my interest, do you have any examples of how this method increased the overall account quality score and the impact it had on ROI?

    17. Kearby Chen Kearby Chen says:

      Hey Scott, since account quality score is a factor for calculating keyword quality score, it’s not something we can measure directly; however, keyword quality scores (and overall ROI) should improve over time. Deleting the appropriate keywords and tracking the changes within individual accounts is something we haven’t looked into yet but may be coming in a follow-up post; make sure to check back later!

      In the meantime, if you followed some of the aforementioned guidelines and see results, feel free to post your findings here!

    18. Trung Ngo says:

      Great article, I just wanted to add and also ask some questions.

      Regarding deleted keywords that might lower your QS, I find that sometime my 3-4 QS keywords brings in more sales and at a much lower CPA than my 7-10 QS keywords, so what I usually do is bring these keywords into another adgroup or even campaign so that their QS will not affect the current campaign with many high QS keywords. Now my question is that when I do this, will it still affect my account as a whole or will it just affect each campaign individually?

    19. Kearby Chen Kearby Chen says:

      Hi Trung,

      Keyword QS at the most basic level is a measure of how relevant a particular keyword is to the ad creative and landing page it’s associated with. By selectively moving lower QS keywords into separate ad groups, there is an opportunity there to create and test (a) more relevant version(s) of ad creative(s) and thus improving the QS of those keywords.

      Over time, this should affect and hopefully improve the account as a whole since historical performance at the account level is a factor of QS but individual campaign performance is not.

      I hope this helps!

    20. Thanks for sharing this, it’s a very interesting topic. I still have some open questions:

      - If I get you right, in case A (Deleting Keywords Without an Impression) you tell us about the impact of deleting keywords with more than 2 impressions in one year and more than 17 days between first and second click (=> the account would lose about 1.0% of long-term sales and save 1.1% of long-term costs). What would be the impact of deleting keywords with no impressions at all?

      - It is an interesting finding that the factor Sales:Costs is identical in case A and B (10:11). I would have guessed that it would be lower in case B, as these keywords should typically have a higher CPC (due to low quality factor of keywords with low CTR (B) & little competition on keywords without impressions(A) ). Is the conversion rate in case B higher and compensates high CPCs?

      - Did you observe a significant increase in the remaining keywords’ quality factor in case B (Deleting Keywords Without a Click)? That would be really interesting.

      - Finally, I do not understand this 99.99% thing. Do you really mean that there are accounts where 99.99% of the account traffic comes from keywords that had very low CTR in the beginning (2.5 years between first impression and first click)??? Or do I get it completely wrong?

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