I think that the point is that both the pollsters and Nate are looking at how various polling methodologies correlate to actual past election results. The raw

I think that the point is that both the pollsters and Nate are looking at how various polling methodologies correlate to actual past election results. The raw numbers from a poll are no good though, because you have a biased sample. The people who answer the survey are not representative of the people who show up to vote. They use the actual election results to calibrate the correction for this. As long as these relationships stay stable, polls should be pretty accurate. In my understanding, the biggest problem in 2016 was that the polls were undercorrecting for the difference between college educated voters vs. not college educated voters. Historically, this made less of a difference than other factors in voting behavior, so it had less impact in the weighting model. In 2016, it had a lot of impact, and college educated voters were more likely to answer the survey, so their tendency to vote Hillary was overrepresented in the polls. That said, the polls were off by less than 2% nationally. Perhaps that's not a great result, but it's not as if they were wildly wrong, it was just a close election. Unfortunately this election is also somewhat close this year, and voting behavior is going to be different with the pandemic, mail in voting, etc. I think it's very hard to reliably call Pennsylvania.