When Spencer Rascoff, the chief executive of Zillow, was asked recently about the accuracy of the website’s property value estimates, he answered that nationwide the Zestimates have a “median error rate” of about 8 percent. But localized median error rates on Zillow, the most popular online real estate information site, sometimes far exceed the national median, raising the odds that sellers and buyers using the site will have conflicts over pricing, the Los Angeles Times reports.