• http://www.andykuiper.com/ Andy Kuiper – SEO Analyst

    Thanks Kohki :-) I especially found interesting this takeaway: “..a quality score difference of 1 had a 5% effect on average CPC for a keyword when controlling for bid and average position.”

  • http://twitter.com/kohkiyamaguchi Kohki Yamaguchi

    Glad you found it interesting, Andy! The exact percentage probably
    varies depending on account and vertical, but most studies seem to see
    somewhere in between 5% to 10% effect on CPC for each QS unit.

  • http://www.facebook.com/mr.larry.kim Larry Kim

    wow great stuff

  • http://www.toptiertools.com/ Frederick Vallaeys

    Great data Kohki! I’m sorry I missed your talk in Seattle about this… We just did a few tests at Optmyzr with our Quality Score Tracker tool and we found that there is a bigger shift in CPC in the lower range of QS. So moving from QS 4 to 6 has a bigger impact on average CPC than a move from QS 7 to 9.

    It’s also true that Google does position normalization so like you said, an increase in CTR due to a better position is not a guarantee that quality score will improve.