This may be an obvious fact for many Google AdWords professionals, but I am sure many people do not know this. According to a Google AdWords representative, Google only uses exact match data for quality score analysis data.
AdWordsPro Sarah said in a Google Groups thread,
Match types does not affect Quality Score (we only collect Quality Score data when the query matches the keyword exactly. The exact match Quality Score is then shared with broad and phrase match).
So, if you are bidding on [blue shoes] and you get a click from a search on [red shoes], due to broad match - then Google won't use that click for quality score purposes. Google will only use the exact match of a click, i.e. [blue shoes] search to [blue shoes] keyword ad. It doesn't mean Google won't rank your broad or phrase match ads based on your overall quality score. It does mean that your overall quality score is made up of only exact matches.
Forum discussion at Google Groups.
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rustybrick in Google AdWords at July 17, 2008 8:34 AM
Comments (2)

Comments
I believe you have a mistake in this write up. If you are bidding on if you are bidding on [blue shoes] you should never match on [red shoes], broad or otherwise. A better example would be bidding on [blue shoes] and matching [blue suede shoes]. So your Quality Score would only count when someone Googles and matched exactly [blue shoes].
Posted by John Allen at July 17, 2008 17:50