General Discussion
In reply to the discussion: Bad News: Trump's support is rising [View all]pnwmom
(108,975 posts)It doesn't use a random sample of Americans or of voters. It's not a poll with a certain "margin of error."
It's just a lot of people who answered an online poll. From a link on the Reuters site:
https://www.aapor.org/Publications-Media/Press-Releases/Archived-Press-Releases/Understanding-a-credibility-interval-and-how-it-d.aspx
The statistical basis for a poll to have a margin of sampling error is that it must be based on a probability sample, where everyone in the population to be surveyed has a chance of being selected and the respondents are selected randomly. Surveys based on self-selected volunteers such as opt-in online polls do not have such a grounded statistical tie to the population. As a result, estimates from self-selected volunteers are subject to unknown error that cannot be measured.
A credibility interval can be developed to measure the theoretical accuracy of nonprobability surveys. The credibility interval relies on assumptions that may be difficult to validate, and the results may be sensitive to these assumptions. So while the adoption of the credibility interval may be appropriate for nonprobability samples such as opt-in online polls, the underlying biases associated with such polls remain a concern.
Consequently, AAPOR urges caution when using credibility intervals or otherwise interpreting results from electoral polls using non-probability online panels. The Association continues to recommend the use of probability based polling to measure the opinions of the general public.