Predicting the 2020 Democratic Primary is Stupid | Pt 2. Correlation is not Causation
Since 1980, the Iowa Caucus has correctly predicted the eventual Democratic Nominee every time except once, in 1992.
Of those Democratic Nominee predictions, 3 won the popular the vote (Al Gore, Barack Obama and Hillary Clinton). The rest were crushed in electoral landslides (Walter Mondale, Mike Dukakis, John Kerry).