One of FiveThirtyEight’s goals has always been to get people to think more carefully about probability. When we’re forecasting an upcoming election or sporting event, we’ll go to great lengths to analyze and explain the sources of real-world uncertainty and the extent to which events — say, a Senate race in Texas and another one in Florida — are correlated with one another. We’ll spend a lot of time working on how to build robust models that don’t suffer from p-hacking or overfitting and which will perform
Source: When We Say 70 Percent, It Really Means 70 Percent | FiveThirtyEight