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Sampling

Sampling. 12/6/2012. Readings. Chapter 8 Correlation and Linear Regression (Pollock) ( pp 199- 206) Chapter 6 Foundations of Statistical Inference (Pollock) ( pp 122-135). Final Exam. SEC 1 December 12 th (Wednesday) 1:30 pm - 3:30 pm SEC 2 December 11 th (Tuesday)

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Sampling

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  1. Sampling 12/6/2012

  2. Readings • Chapter 8 Correlation and Linear Regression (Pollock) (pp 199- 206) • Chapter 6 Foundations of Statistical Inference (Pollock) (pp 122-135)

  3. Final Exam • SEC 1 • December 12th (Wednesday) • 1:30 pm - 3:30 pm • SEC 2 • December 11th (Tuesday) • 1:30 pm - 3:30 pm

  4. Final Paper • Due 12/7/2012 by 11:00AM- Doyle 226B • Turnitin Copy by 11:59PM on 12/7

  5. Reminders for the Paper • Paste outputs into the paper as images • Dataset information is in Chapter 1 and in the appendix. GSS and NES also has information on line • If running x-tabs don’t forget column %’s

  6. Opportunities to discuss course content

  7. Office Hours For the Week • When • Friday 11-1 • No office hours during final exam week

  8. Course Learning Objectives • Students will learn the basics of polling and be able to analyze and explain polling and survey data • Students will learn the basics of research design and be able to critically analyze the advantages and disadvantages of different types of design.

  9. Data Collection Method I Personal Interviews

  10. Cluster Sampling (How we conduct it) • People Move, Houses Don’t • Random Samples of known units • Each unit in the cluster has a chance

  11. Personal Interviews • Advantages • Disadvantages

  12. Method II Mail Surveys

  13. Collecting a Sample • Every address is in our frame • Often Used to target specific Groups • Less popular for “hot topics”

  14. About Mail • Advantages • Disadvantages

  15. How Most Surveys are Done Today Telephone Surveys

  16. Telephone Surveys • Every Phone Number has an equal Chance of Being Selected • It is important that you select the right people

  17. Advantages of Phone • Fast • CATI • Closed Ended Questions

  18. Why it is not a true random sample • Some people do not have phones • Some people simply will not answer (75% refusal rate)

  19. Surveys miss out on • Poll Sampling excludes many—minorities, young people, and new Americans • Angry White Men

  20. Who we often get

  21. Problems of Cell Phones • Some polls Exclude them • You have to pay people to participate • Some polls contact you and ask you to call back

  22. This makes it less random We have to survey a lot more people than we used to

  23. Not All Sampling Frames are Created Equal

  24. Low Response rates and trying to get likely voters slow things down and drive up costs.

  25. Other surveys

  26. Modern Internet Surveys • Combine RDD and the Internet • Very Fast • Problems (24% do not have internet access)

  27. Exit Polls • Use a random selection of polling places • Quick Recall and Fast Data • Problems (early voting)

  28. So Should we follow the polls?

  29. Verify all Polls • Who Conducted it • How many they sampled • How they sampled • Specific question wording

  30. In 2012, they were pretty good

  31. Always Check • Who sponsored the poll • How they got the sample • How big was the sample • Specific questions

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