ComputerGeek said:
Why is Exit Polling considered accurate for so many years in the US, and is used as the standard by the UN to determine the validity of an election.
I'm not sure how the UN uses them, but in the US, they have never been used to determine the validity of an election. Their purpose is informational - and they even use the election results to correct the errors in the exit polls! Don't confuse what the news media does with exit polls with a real check of the election results. The primary purpose of exit polls is not to show
who someone voted for, but
why and because of that, the demographic information (age, sex, race) is used to adjust the poll results to match the election results by demographics, thereby improving the accuracy of the election poll's main goal: to explain why people voted the way they did.
IIRC, those studies that we discussed months ago misused the data in another way: they used the uncorrected data, while the results from previous years match their election results because they were
made to match the election results.
Don't make the mistake of comparing close elections with not-so-close elections (ie, Reagan's sweep). Margin for error plays a big role here: If someone wins by 10% with a 2% margin for error, the margin for error doesn't mean a whole lot, but if someone wins by 1% with a 2% margin for error (all numbers hypothetical), the margin for error makes a big difference.
Also, don't make the mistake of falling into the flying saucer fallacy: UFO does not automatically equal flying saucer and results that don't fit doesn't automatically mean fraud.