Every number we put on the site comes from somewhere. Here is where, along with what we think of each source.
James Oldroyd, Kristina McElheran and David Elkington, "The Short Life of Online Sales Leads,"Harvard Business Review, March 2011, with MIT. Over 15,000 leads across six companies. Firms responding within five minutes were 21 times more likely to qualify a lead than firms responding after thirty.
Our note: it is a 2011 study, and we would rather tell you than hope you do not check.