Election polls often tighten up remarkably as the election date draws near. “Leave” (the European Union) won the UK election of May 2016 with a majority of 51.9%, but earlier the polls weren’t nearly as tight—in January 2011 “Remain” was up by about 20 percentage points. In the 2020 presidential election in Poland, Andrzej Duda won with 51.0% of the votes, whereas he was up by about 5 percentage points just eight weeks earlier.
Why do large electorates tend towards evenly split results?
