xurxo - 4:30 am on Oct 21, 2008 (gmt 0)

cyberandroid is right. Since adwords is not a pure auction-based model, you'll have to make sure to include the negative exact matches -[keyword] inside of your adgroups containing broad and phrase matched keywords. This is to make sure that your traffic is being allocated to the proper keywords and adgroups.

If you don't include the negative exact matched keywords, then you could see a broad or phrase matched keyword getting impressions and clicks for exact matched queries that should be triggered by your exact matched keywords. One of the reasons why this happens is because your broad or phrase matched keyword could be graded with a higher quality score than your exact matched keyword even if you were bidding the same amounts on all match types.

There are other variables at play that will influence the quality score, but the setup that cyberandroid described will help you identify which keywords perform well traffic-wise and you'll be able to adjust your bids with better data. Not to mention your conversion data will be cleaner as well.