What is the date that the polls were going on at quinnipiac when john mccain was the republican, barack obama was the democrat and the sample size was bigger than 1427?
CREATE TABLE "connecticut" (
  "poll_source" text,
  "sample_size" real,
  "margin_of_error" real,
  "date" text,
  "democrat" text,
  "republican" text
);
SELECT "date" FROM "connecticut" WHERE "republican"='john mccain' AND "poll_source"='quinnipiac' AND "democrat"='barack obama' AND "sample_size">1427;