A Closer look at Quality Score

By Scott Liu Paid Search Coordinator, Advertising Solutions

In the Search world, search engine has a “Black Box”—its complex algorithm which determines what organic results should be ranked higher according to the query/location/user’s preference. And Quality Score is that “Black Box” in paid search. It’s a constantly updated value that determines whether and where your paid ads should be appearing, as well as how much you’re going to pay for each click. Most search marketers probably don’t look at quality score as often as other major KPIs. However, the truth is, Quality score can be the secret source that improves your overall campaign efficiency.

Define Quality Score

Google--- Google had a big update to Quality Score (QS) last summer, which makes QS a dynamic value that will be calculated at the time of each search query. Here’s how Google defines QS, “It looks at a variety of factors to measure how relevant your keyword is to your ad text and to a user's search query. A keyword's Quality Score updates frequently and is closely related to its performance. In general, a high Quality Score means that your keyword will trigger ads in a higher position and at a lower cost-per-click (CPC).”

Yahoo--- Yahoo has its own “Quality Index” (Shown on a scale of 5 at ad level), the official definition looks slightly different, but the idea is the same—this is the key factor that determines your ad rank and CPC.

Bing--- Bing/AdCenter doesn’t show QS information just yet. According to them, a Bing keyword quality score can have one of the following 3 values, OK, Poor and Not available. And “The keyword quality score feature is part of an AdCenter invitation-only pilot program and is not yet available to the public.”
We’ll take a closer look at how Google handles QS, since Google is the one that has provided most information about QS to advertisers.

Economics of the Quality Score

So why does QS exist? Who gets the benefit from this secret metric?

QS wasn’t introduced when Google started their sponsored ads platform. It used to be just straight bid-to-position model without “Black Box”: the top position belongs to whoever is willing to pay the highest amount per click. As paid search became more and more popular among advertisers, engines realized that the old model probably won’t work since the top ads might have nothing to do with what the user is looking for. Search engines have to find a way to balance the interest between users, advertiser/publisher and search engine itself.

That’s where the QS come into play, giving the user the best results possible and let advertisers get the most relevant traffic at a relatively reasonable price. After the QS concept is incorporated into the paid search algorithm, the engine might be making less money per click on average. But obviously in the long run, this would be the secret source to maintain a healthy competitive marketplace.

Why QS is so important to advertisers?

QS is important because of its prominent role in calculating Ad Rank (Ad Rank=Max Bid * QS), which translates to your ad position for every query. Here is an Official video that helps explain the point. In addition, QS becomes even more important when it comes to determine your CPC—because your ad only needs to pay a price that’s high enough to beat the competition, your CPC is decided by only 2 factors, the ad rank of the advertiser below you and your own QS! Although max bid change could possibly help you improve the ad position, it doesn’t have a direct impact on your actual CPC. By improving your QS, you could pay less for higher ad positions. With that being said, QS data could be very helpful when you’re doing bid management and optimizations.


  • Quality score varies by location. Same keyword might perform better in the U.S. than Canada. Therefore it might have a higher QS for searches in U.S.
  • Google and Google search network might have different QS for the same keyword.
  • QS data is only recorded for a particular keyword when the query exactly matches the keyword, which means match type does not have a impact on QS. (We learned this from our Google reps. But it was not part of Google’s official explanation about QS)

My Speculation

Google gives us some ideas of what’re the main influencers for QS, but it is far from clear and specific. And Google probably would never disclose that type of information to public, just because that’s one of the core pieces of their paid search business. One thing for sure in my opinion, search engines will continue to improve the QS technology in order to provide better results to users and relevant traffic to advertisers.

Something like Quality Score optimizer platform is already in the marketplace.

What’s next?


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