Robert Cahaly, senior strategist for the Trafalgar Group, made a name for himself in 2016 by being the only pollster to correctly show Donald Trump with a lead in Michigan and Pennsylvania -- two key states he carried -- heading into Election Day. (He did not poll Wisconsin, another surprising win for Trump.) Cahaly also showed Trump ahead in North Carolina and Florida, both of which he won, securing his improbable 304-227 Electoral College victory over Hillary Clinton. Cahaly managed to pick up support for Trump that all other pollsters missed by employing a unique method that sought to measure...