1.https://adwords.google.com/support/...5&query=quality+score&topic=&type=f& onclick= 2.https://adwords.google.com/support/bin/answer.py?answer=21375&ctx=sibling
Basically quality score is relevance and CTR You can check it 2 ways 1. in the keywords tab where you see all your keywords, unhide the column that says quality score. The score is either Poor, OK or GREAT 2. You can assess QS by looking at the min bid google sets for each keywords. 0.05 min bid requirements are GREAT QS scores while 0.15 is OK and .50 is POOR. Many people will lead you to believe the QS = CTR but that is incorrect. CTR effects QS but CTR is not an indicator because 15% CTR can equal a POOR QS while 0.50% CTR can equal a GREAT QS. Why? Because is position and keyword relevant. Google knows that some keywords naturally get higher CTR's and also knows that pos 1 will get a better CTR than pos 7