What is the basis of the classification of each race?
Regardless of the number of polls, we calculate a “confidence intervals” around the trend estimate based on the average sample size for the available polls in each state. These intervals reflect the uncertainty in the estimate due to random noise in the polling data. If a race shows a lead that is outside the 95% confidence interval, then we classify this as a “strong” lead. If the lead is between the 68% and 95% confidence intervals, then we classify it as a “lean”.
