What if your search ad is really what converts a searcher and the landing page only confirms the impression?   According to Johathan Mendez that is what actually happens - and he’s got the case studies to prove it.

First - you conversion happens on the ad, not the landing page.

"The best way to leverage this interest is to reinforce the messaging in the ad on the landing page. Obviously the user liked what you said enough to click through. Make sure you bridge that second or two of page load with reinforcement of the original messaging. A second or two in the flow of a user experience is more than enough time for the user to lose focus or become distracted. Again, many tests have validated the effectiveness of messaging reinforcement (not only on the landing page, but throughout the conversion funnel)."

The title (keyword) first line, description all need to be just right. 

I bring this up because I look at content and effectiveness for my clients, esp my corporate clients.  In one case I was asked to produce all the metrics that would determine the success of a promotion on the week(s) that it ran.  Each promotion fell into a predefined category and each occupied a position in the corporate portal page.

Our contention is that the type of ad would make the difference, or the position on the corporate portal would make the difference - but at the end of the day it’s the content that makes the most difference between the effectiveness of an ad and it’s click through.