Your account quality score is used in several places within your AdWords account:

• Keyword quality score
• Ad Group quality score
• Minimum bids for existing keywords
• Setting minimum bids for new keywords

The account quality score is a small factor when determining keyword and ad group quality scores. It can help to remove under performing keywords, however, it should be noted that this is only a small factor compared to the other items that determine keyword and ad group quality scores.

The main purpose of the account quality score is for setting minimum bids when Google does not have a lot of information about that keyword.

If you are in the medical industry, or an industry with a lot of jargon, Google doesn’t necessarily have a lot of history about that keyword. This is especially true for brand new terms such as new products or recent discoveries.

So, for industries without a lot of search volume and history, a high account quality score will help lower your minimum bids when you introduce new keywords.

Essentially, if you have a high account quality score, Google is trusting that you respect the user experience and gives you more leeway with new keywords. If you have historically not had a high quality score, and thus what Google considers a lower user experience, they aren’t quite as forgiving for new keywords.

The account quality score is determined much like the ad group quality score, just on a more global level. All of the keywords in your account are ‘rolled up’ and aggregated to determine what your account quality score is.

The keywords are normalized for impressions and clicks. So, keywords with 1 million impressions and tens of thousands of clicks with weigh much more heavily than keywords with hundreds of impressions and tens of clicks.

Therefore, the factors that determine your account quality score are identical to the factors that determine your keyword quality score (with the exception of account quality score).

• Click through rate on Google.com
  • Overall history
  • Most recent history
• Ad copy
• Other relevancy factors

Please refer to the full list of AdWords Quality Score Factors for an explanation of each factor type.

While the account quality score should not be completely ignored, if you are in a well established industry, improving the account quality score might not make a huge difference in your account.

If you are constantly adding new keywords, trying to bid on hundreds of thousands of keywords, or are in an industry where new keywords appear on a regular basis, improving your account quality score will make a huge difference in the initial minimum bids.