Sampling is based on probability theory --in its broadest sense, if we can choose respondents randomly and appropriately from the larger population, the results from that random sample will be very close to what we would get by interviewing every member of the the population.

(NOTE: The following information on sampling was developed by AAPOR as part of a comprehensive online journalism polling course created in partnership with NewsU, a project of the Poynter Institute and funded by the Knight Foundation. The course launched  September 2007.)

• Why Sampling Works
• Margin of Sampling Error
• Good Samples
• Bad Samples
• Weighting

Additional Resources

• A Guide to Sample Size and Margin of Error -- Public Agenda
• "How Poll Sampling Works" - Online Journalism Review
• Sample Size Calculator
• CBS News Polling Director on Sampling