By using this site, you agree to our Privacy Policy and our Terms of Use. Close
sc94597 5 days ago
Edit Thread
Cerebralbore101 said:

I don't think they've ever fixed polling errors. Trump has beat the polls the last two election cycles. I hope I'm wrong. But I've just lost hope for this country.

Edit: Also the below makes no sense. What are you saying?

We're likely going to see a situation where the conservativeness of the pollsters this cycle will (not?) make any single pollster more accurate, but the aggregation of polls less accurate because they're likely underestimating the winning candidate, systematically. This could be Trump or Harris. Past cycles tell us nothing about where this systematic error resides, because of the bolded point at the start of this post. 

I already explained why we should expect that they have fixed the old polling errors. They fundamentally changed the sampling and weighing methodology, and Trafalgar/Rasmussen are closer to the polls that had the Trump under-representation, this cycle. More evidence to that point is that in 2022 they overestimated Republican chances and the supposed "red wave" never happened. 

In response to your edit.

Imagine you have the following scenario. The true value that is being predicted/estimated turns out to be 51%. 

But let's say using methodology 1, you have pollsters with final predictions of: 49%, 50%, 50.5%, 48%, 52%. The error of each pollster is: -2%, -1%, -.5%, -3%, and +1% respectively. The average prediction is 49.9% (-1.1% error.) 

Now let's say using methodology 2, you have: 47%, 54%, 48%, 52%, 51% The error of each pollster is: -4%, +3%, -3%, +1%, 0% respectively. The average prediction is 50.4 (-.6% error.) 



You can see now how each pollster could be more accurate while their aggregation is less accurate?

Edit: 

To expand, the MAE (mean absolute error) for #1 is 1.5%. The MAE for #2 is 2.2%. But the error by taking the average of predictions is: -1.1% and -.6% respectively. This is a situation where each individual pollster has a closer value to the actual, but the aggregate is further off because the direction of the error matters, and can cancel out. 

Edit 2: Added a picture. 

Blue-line is the actual, purple line and dots are scenario 2, green lines and dots are scenario 1. Purple estimate is closer to blue actual, despite some purple dots being  much further from it. 

Last edited by sc94597 - 5 days ago