From Professor Charles Franklin, of the University of Wisconsin, publishing at www.pollster.com, the following graphic illustrates how far from perfect each of the  pollsters who worked the South Carolina Republican Primary were.

A perfect pollster performance would be at the intersection of the horizontal and vertical lines on this target. Only SurveyUSA, of the polling firms competing in South Carolina, was inside the first ring of the BullsEye.

Additional analysis by Professor Franklin, and context for interpreting this graphic, is available at the Pollster.com website, here.