General Discussion
In reply to the discussion: Reuters: Democratic support for Hillary drops 15 points since February [View all]DemocratSinceBirth
(99,710 posts)What makes a poll random is that every type of person has an equal chance of having their views captured.
While we appreciate people who want to participate, we cant base our polls on volunteers. A survey of volunteers is a non-probability sample and the results cannot be generalized to the public as a whole. The key to survey research is to have a random sample so that every type of person has an equal chance of having their views captured. Polls of volunteers would violate this principle since not everyone would have had an equal chance of being included.(See probability and non-probability sampling for more information.) And more specifically, the kinds of people who might volunteer for our polls are likely to be very different from the average American at the least they would probably be more politically interested and engaged.
http://www.pewresearch.org/methodology/u-s-survey-research/frequently-asked-questions/