When it comes to Internet advertising, the more data the better.
In early October, Google made available a feature which enabled advertisers to combine Google Analytics data directly within Adwords accounts. If you haven't done that yet then you should - it has been a virtual blessing for those seeking ways to improve their campaigns and achieve an ever more elusive return on advertising spend.
Advertisers that set up their Adwords account to import Google Analytics data now have access to metrics including bounce rate, pages per visit and average visit duration. Why are these metrics important to a paid search advertiser? Two reasons: one, they are determining forces in quality score (which influences how much advertisers pay and where they are positioned on the sponsored SERPs), and two, they serve as foolproof indicators of how well advertisers are engaging users arriving to their sites from paid search ads.
For example, say you are analyzing and testing two keywords. Both received the same number of impressions, but one had a much higher CTR and a far higher bounce rate. Knowing this information would provide the advertiser with the empirical eveidence they need when deciding whether to drop the underperforming keyword, make landing page adjustments to ensure visitors don't bounce (via improving relevance) or increasing their bids and optimizing for those keywords that drive engagement exclusively.