Why do large electorates tend towards evenly split results?

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.

This article was originally published here