As much as we wish we could, we can’t.  Nobody can.  And if they say they can, I’d question their methods.  Again, visitors to your site are real people and we cannot dictate or control human behavior/response to what happens once they reach your site – that includes sales, signups or click throughs.  That said, many of our longtime customers continue to see a positive ROI to the extent they keep their website content fresh and relevant with compelling messaging and calls to action.