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The importance of CTR to QS

By Paul Morris
I’m going to be succinct (it might look like a long post however have a look at the supporting data and you will find it is succinct!) with this post as it’s more for me to show others the importance of Quality Score (QS).

Note: This post has been bastardised from other posts, particularly from the Wordstream blog, hence all the real work has been completed by others; I have merely plagiarised.


Strong positive correlation between QS and click-through rate (CTR) — the higher your CTR, the higher your Quality Score.

graph 1 quality score and click through rate


Quality Score is normalized by ad position i.e. ads in more prominent ad positions are naturally going to enjoy higher average CTR hence Quality Score is normalized to compensate for performance differences resulting from ad position. What is interesting though is if you break down the relationship between Quality Score and CTR; in this case with average ad positions of between 2.1 and 2.2

graph 2 Quality Score

And now for campaigns with average ad positions of between 4.1 and 4.2

graph 3 quality score

Key take out for me is that the slope of the line is much higher in the directly above diagram than the one above that. i.e. when you’re in a lower ad position, smaller increases in average CTR result in larger increases in average QS.

And if you are after more info on what determines QS then study the great article by Frederick Vallaeys

To super summarise Frederick’s post (and I would encourage you to digest his post in detail):

The following chart shows clearly the direct correlation between QS and CPC:

graph 4 QS and CPC

Now onto a nice chart that shows/ eludes to the fact that account QS and domain QS still play a key role for keywords that are new to an account.

graph 5 account qs

Whilst ‘newer’ factors such as landing page quality in QS is growing in importance (key factors are bounce rate and time on site) the reality is that CTR still rules the QS roost.

And after all that if you want to see more working examples then see my AdRank Quality Score & CPC Explained post

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