I have two identical campaigns, one runs in the US the other in Canada - I just wanted to keep them separate. When I first set up the campaigns the minimum bid quality scores for the keywords were generally 1 cent cheaper in the US than they were in Canada. The only difference between the two Campaigns is the display url on the ads. For the US campaigns I use a .com extension and for the Canadian ones a .ca extension (the .ca domain just redirects to the .com where our actual site is). The actual url's for the ads go to identical pages on the .com domain. Most of the keywords are marked great but I do have a few that are O.K. and actually performing quite well so I have kept them on. This is where I begin noticing the difference as I had a couple of keywords inactivated for search on the Canadian campaign. They were showing as OK with a minimum bid of 30 cents. The exact same keywords in the US campaign are also marked OK but with a minimum of 10 cents. I assume that the display url is what is causing this. Is there anything else that could be responsible?
Keyword Quality Score classification is based on the the competition of that keyword across all publishers that bid for that keyword. The US and CA market has not all the same publishers using these keywords and so will be a difference on the bid average value and a difference on conversion rate ratio average for that keyword that will impact the keyword calculation for each publisher that bids on that keyword.
Your clickthrough rate plays a part in your Quality Score, so if your advert has a different clickthrough rate in different countries (adjusted to take into account your advert position), it'll get a different Quality Score. It's interesting that the initial minimum bid is different, though, since this uses Google's estimate of how your campaign would perform. It seems that they correctly predicted that it would work better in the USA. Regarding the size of the difference, if the initial minimum bids were $0.02 and $0.03, and the minimum bids are now $0.10 and $0.30, the difference in your actual Quality Score may be the same.
Having monitored it further it seems that the CTR is having a pronounced effect. Click throughs in the US are much higher than in Canada - glad I decided to run them as different campaigns or I would never have known! I have some ad groups that give nearly 10% CTR in the US and close to Zero in Canada. Fortunately they are not all like this though! As the ads mature and gradually get improved it ceases to be a problem.
It's the mentality of the clicker too...I think a .com would do better in general then a .ca. Especially if you're an american company
That was my thinking too. We are a Canadian company so thought that using the .ca on ads running in Canada would be of benefit to us.