"Margin of error of 9" doesn't mean "It could be [reported result-9] just as it could be [reported result+9]." It just means there's a 95% probability that the result will fall somewhere within that range.
It is Plus & minus 9. It does mean that.
What you are talking about is Confidence Interval. Most surveys are conducted with a confidence interval of 95%.
No, it doesn't. The probability that the result is + or -9 is much, much lower than it will be exactly right or + or -1, for example. Every poll can be turned into a probability forecast, which is what 538 essentially does. The actual probability that it is + or -9 or worse is likely around 5%.
Tony and cinyc are mostly correct. The confidence interval defines the the range that the actual result falls within at some given probability, which is usually 95% for political polls. The MoE is usually defined as half the confidence interval, and that is what political polls report. To the extent that the statistics fall in a normal distribution the MoE and confidence interval are directly correlated. For skewed samples they may not be completely correlated, but that is not as likely in the Dem race with just two candidates both polling more towards 50% than towards 0% and 100%.
muon2 are you supporting trump?
