Controversy on Polling

Politico has an article up today about the SurveyUSA's polling in VA-5, which consistently show Democratic incumbent Tom Perriello trailing his challenger by twenty points or more. The Perriello camp has pushed back, releasing two internal polls that show the race as a dead heat. I am going to that district tomorrow and will have an update in next week's print edition of NCR. But, for now, let's just say that polls must always be examined with grains of salt at hand, because the different methodologies used by pollsters allow for such disparate results.