The best method is probability sampling. 384 is a magic number for many surveys, no matter how large the group if you give a fair opportunity for every member to be polled you can be 95 percent sure that you are within 5 percentage points of a precise reading for a lot of surveys. To survey people correctly you need to take the population and divide it by 384 and then survey every whatever number that is, person. For example if it was 6 you would survey every 6 people on the list of people in that population. Every survey has a margin of error that must be listed. Every survey also has a confidence level that is also typically stated.
Quote sampling is done by surveying quotas of men and women that correspond to whatever they are surveying about. For example within an election you would survey a certain amount of democrats, republicans and independents. However, this has only been close to 4 percentage points where as probability came close to 2 points so it is not as accurate.
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