I have both a personal and a professional interest in the way Extended Validation SSL changes consumer behavior on the sites that use these new SSL Certificates. The personal interest is that since I sat on the CA/Browser Forum during EV's formative stage, I'd like to know if our efforts were successful. The professional interest is a little more obvious but very similar; since we offer these certificates at VeriSign it's very important to determine what effect they have on completed transactions on sites.
First we had the Tec-Ed research, which demonstrated that online shoppers have a natural understanding of the vocabulary of green bars and view EV SSL as a positive thing on a site. That was great early information, but my real interest was in the actual changes in behavior among visitors to real production sites. The first site I discovered to have measured this effect was Overstock.com, who saw an 8.6% decrease in abandonment. Next I found DebtHelp.com, with its 11% increase in transactions. We went on to discover that PayPal, Scribendi, and Virtual Sheet Music had measured the same thing, all with an increase in a site visitor's propensity to complete a transaction when a green address bar is present.
So you may be interested to know that today VeriSign announced the next six sites to measure the affect of EV on their site traffic. They are: