Communications of the ACM (Dec. 2) -- Many people continue to be shocked by the election of Donald J. Trump as the 45th President of the United States. In this age of data analytics, professional pollsters and data scientists did not have their finest moment. While the past several elections have been more favorable to attempts to forecast outcomes ahead of time, that trend failed to hold in 2016. As forecasters attempt to understand exactly what happened, the data itself may hold vital clues (Article co-written by CS professor Sheldon Jacobson).