Google has added claims to its Google Checkout Merchant homepage that having Google Checkout as part of your AdWords ads will lead to higher conversions and a better click through rate. Google specifically writes that conversions will increase by 40% and the click-through-rate on your ads will increase by 10%.
I spotted this via Google Blogoscoped, which has also documented the various Google checkout badges Google has used throughout the years. As you can see, having the Google Checkout badge makes the ad stand out from the other ads. So I am not surprised by the 10% claim. The 40% claim does seem a bit high, but who knows how they came to those numbers.
Postscript: Google has sent Google Blogoscoped a statement on these claims. Let me share it with you because it makes a big difference:
Google isn’t actually saying that there is 10% gain in CTR. It’s saying there is a 10% gain in CTR for “Google Checkout users”.