Undoubtedly in response to numerous questions from concerned and confused Google Adwords advertisers, Google has posted an explanation of its Quality Score changes on its Adwords blog.

In short, here are Google’s responses to the main three issues on advertisers’ minds:

1. How will Quality Score be calculated?

Google will STILL consider (a) the historic performance of you account, evaluating the clickthrough rate (CTR) of all the ads and keywords in that account; and (b) your landing page quality. However, although Google will evaluate your overall Quality Score at the time of each search query, it will evaluate landing page quality less frequently.

2. What’s the impact of the removal of ‘Inactive for Search Status’?

Google believes that by making all keywords active it will better be able to evaluate keywords for any query where they may be relevant. The company has acknowledged that keywords previously marked as ‘inactive for search’ would otherwise never show ads on Google.com, even where they might have been a high quality match for certain queries. Now it’s giving such keywords a chance.

3. What’s the difference between ‘first page bid estimates’ and the old ‘minimum bids’?

Google says that for queries that don’t have much advertiser competition, the first page bid estimate should be relatively close to your existing minimum bid. However, queries with lots of advertiser competition may have much higher first page bid estimates. This is because you’ll probably need to bid above the old minimum bid to rank higher than the competition and show on the first page of paid search results.

Source: Trevor Claiborne, “Quality Score improvements to go live in coming days”, Inside Adwords, September 15, 2008