Why You Should Care About Quality Score

Quality Score is a special metric, calculated by Google for each of your keywords. Google strives to provide the best search experience to its users (why would we use it otherwise?), as well as its advertisers. The aim of this metric is to ensure that users get relevant search results and advertisers are encouraged to deliver efficiently targeted messages at the right time.

A quick explanation from Google sounds like this:

The AdWords system calculates a ‘Quality Score’ for each of your keywords. 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).

Source:  http://adwords.google.com/support/bin/answer.py?hl=en&answer=10215

Quality Score is a dynamic metric, which updates often depending on:

• Historical Click-through-rate of the ads
• Landing page relevance for the search that user performed
• The ads, bids and landing pages of the other advertisers (the competitors) for the same keyword
• The relevance of the keyword to the ad text

Let us consider one of the PPC accounts I managed over time. The  distribution of the Quality Scores for all of the keywords in this PPC account looks as follows:

Now, let us have a closer look at the performance of the keywords with Quality Scores, which are the most common for this particular account – these are Quality Score equal to 7 (61% of the overall distribution), Quality Score equal to 6 (11%) and a Quality Score equal to 10 (10%).

The click through-rate is one of the factors to calculate the Quality Score, so the better it is, the higher Quality Score  keywords get:

Google claims, that each click costs you less,  if you have a good Quality Score. The real costs for the account under consideration are re-calculated to the nominal numbers, to demonstrate the relative cost-per-click for the keywords with different Quality Scores. And below is how the those costs per click look like:

Note, that  average cost-per-click is slightly higher for the keywords with Quality Score 10 – this might be attributed to the dynamic nature of Quality Score, but also to the fact of high competition.

Now, is there a dependency between the Quality Score and the actual performance of the ads? Look at the below graph, which demonstrates the relative performance (in terms of costs per conversion) of the keywords with different Quality Scores  (again, real costs are re-calculated to the nominal numbers):

This graph above clearly displays, that keywords with higher Quality Score do bring conversions at more attractive prices.