So how did pollsters do in 2020?
After 2016, pollsters worked to fix problems
After the 2016 election, we worked with political scientist Aaron Weinschenk to release analyses, revealing 2016’s final, national pre-election polls were actually more accurate than they had been in 2012. They pretty closely forecast the popular vote, even if Donald Trump snagged victory in the electoral college. We found a slight pro-Democratic bias that was mostly not statistically significant.
That suggests that, overall, the 2016 national pre-election polls were generally accurate and unbiased. That year’s state-level polls similarly underestimated Republican support, but here too these biases were generally statistically insignificant. The larger problem — at least for those who wanted to know the outcome in advance — was too few quality statewide polls in key battleground states, compared with previous years.
Nevertheless, the discrepancy between poll projections and the eventual outcome pushed many pollsters to reconsider