Polling performance for the 2020 election between Joe Biden and Donald Trump. Relative error is a metric for evaluating the accuracy of poll predictions relative to actual voting outcomes. Relative error is calculated as (observed−expected)/observed, where the “observed” value represents actual election results, and the “expected” value denotes the predicted results from polls. This statistic helps to identify the proportion by which polls under or overestimate support for a candidate. In this figure, a positive relative error indicates that the polls underestimated the candidate’s actual support, while a negative value suggests an overestimation.