Attribution
Quality Score
Also called ad relevance score.
Quality Score is an ad platform's rating, on a scale of about 1 to 10, of expected click rate, ad relevance, and landing page quality. It affects what you pay and where the ad appears.
How it is measured
The platform estimates three parts: how likely the ad is to be clicked, how well it matches the query, and how good the landing experience seems. The rating is per keyword and is shown in the ad account, not in analytics.
Read the three component ratings, not the single number. A low score with a low expected click rate needs a better ad, and a low landing page rating needs a better page.
Worked example
A hardware chain has a keyword, 'cordless drill set', rated 4 out of 10, with a CPC of $2.80 and average position 3.5. Below average on landing page experience.
The team builds a page that lists drill sets with specs and a comparison table. In three weeks the score reaches 7, CPC falls to $1.90, and the ad holds position 2.4 with the same bid.
How it differs
Quality Score is a platform rating. Click-through rate is an observed result and one of its inputs. The score is the platform's estimate; the rate is what happened.
Common errors
Treating it as a goal in itself. Ignoring the component ratings. Judging every keyword by it. Changing ads without checking the page. Assuming other platforms use the same scale.
In practice
Pull the keywords with the highest spend and a score under 6. Read their component ratings and fix the weakest one first. Re-check after a few weeks.