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JAMM 444: Public Opinion

JAMM 444: Public Opinion. Survey methodology Comparing survey methods Planning your surveys. Tuesday, Sept. 19. Schedule update Survey methods Sources of error Meet in small groups: team project. Schedule update. TODAY: Chapter 3, Survey methods

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JAMM 444: Public Opinion

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  1. JAMM 444: Public Opinion Survey methodology Comparing survey methods Planning your surveys

  2. Tuesday, Sept. 19 • Schedule update • Survey methods • Sources of error • Meet in small groups: team project

  3. Schedule update • TODAY: Chapter 3, Survey methods • Thursday: Chapter 9, Using public opinion data • Sept. 26: Barbara Foltz & Stephanie Kane, UI Social Science Research Unit • Sept. 28: Valerie Steffen, president, Strategic Intelligence (Boise)

  4. Survey methodology Why do a survey? • Measure opinion of a population too large to contact individually • Save time, save money • “Surveys can be used in a scientific way to realize the great benefits of interviewing a representative sample instead of the whole population.” • Salant & Dillman, 1994

  5. Surveys work, if... • Sample is large enough to yield desired precision. • Everyone in population has equal chance of being selected. • Questions enable respondents to give accurate answers. • Sampled respondents have similar characteristics to non-respondents.

  6. 5 key elements of a survey • Population • Type of sample • Method(s) for gathering data • Questionnaire • Analyses and inferences

  7. 5 steps for a successful survey • Be specific about what new information you need and why. • Understand, avoid 4 kinds of error. • Choose the best survey method. • Write good questions. • Test questionnaire before beginning real survey.

  8. Choosing a sample • Identify population of interest: • University of Idaho students • Moscow residents • Idaho voters • ‘The American public’

  9. Choosing a sample • Non-probability sampling • 1936, Literary Digest • Probability sampling • Simple random sampling (rarely used) • Systematic random samples (every 30th name in student directory) • Stratified sample: divided into groups (strata) • Cluster sampling (spread over a wide area)

  10. Cluster sampling • Used for many national surveys: • National Election Survey (NES) • General Social Survey (GSS) • Gallup Organization • 350 geographical segments • Sample to reflect U.S. as a whole (geographic area, size of community) • Random telephone numbers in each area

  11. How big is a typical sample? • UI or Moscow: 200 to 500 • Idaho: 500 to 800 • National: 800 to 1,200

  12. Four sources of error 1. Coverage error: Not allowing every person in population equal chance of being sampled. 2. Sampling error: Only some members of study population are asked to respond. (Range of possible results)

  13. Four sources of error, cont. 3. Measurement error: inaccurate answers due to improper question wording 4. Non-response: Some people in sample don’t respond; different from respondents

  14. Sampling error • The probable difference in results between interviewing everyone in the population vs. a scientific sample taken from the population. • Expressed as “plus or minus X percentage points” http://www.ncpp.org/qajsa.htm#11

  15. Sampling error • See explanation, note, p. 79, PO • Rules of thumb: • The closer the margin, the larger the sample that is needed to reduce error. • For very large populations, a relatively small sample can produce reasonably accurate results. (See overhead)

  16. How large a sample do you need? The answer depends on: • How much sampling error you can tolerate • The size of your population, if the population is small • How varied the population is • The smallest sub-group that you are likely to analyze

  17. Survey methods • 1. Face to face • 2. Telephone • 3. Mail • 4. Internet • What are advantages & disadvantages of each method? Consider: cost, time, response rate, amount of information

  18. For Thursday • Read: • PO9: Public Opinion & Policy Making

  19. Small Groups • Team 1: UI issue or controversy • Team 2: Moscow or Latah County issue or controversy • Team 3: Political knowledge and/or civic engagement by UI students • Team 4: Idaho state candidates or U.S. House of Representatives races • Team 5: Idaho state ballot issues

  20. Small Groups • Meet in groups for at least 15 minutes • Refine your topic • Brainstorm target population, survey methodology, timetable • Choose time and place to meet again before Sept. 26

  21. Small Groups ONE-PAGE MEMO due Sept. 26: • Choose a name for your group (e.g., Bird’s Eye Consulting) • List names of all participants. • Rationale for survey (why?) & target population (who?) • Topics or candidates (what? who?) • Methods (how?)

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