Class 18 Standard Error: Errors in sampling

Discussion: Polls

  1. The results of the WMUR-TV poll we discussed last time.
  2. Read the 1996 presidential poll, what do you think about the questions?
  3. NewYork Times article (10/26/95): "Americans reject big medicare cuts, a new poll finds".

    Read the part in the box "How the poll was conducted". It says that the error is 3%, how do they get that?

Standard Error: Errors in sampling

  1. An introduction to standard error
  2. Discuss the Bean-counting experiment.
groups # of beans in the sample # of White beans in the sample % of white beans in the sample Margin of error 95% Confidence interval
1 430 253 58.84 4.75 (54.09,63.58)
2 689 347 50.36 3.81 (46.55,54.17)
3 242 137 56.61 6.37 (50.24,62.98)
4 739 399 53.99 3.67 (50.33,57.66)
5 724 432 59.67 3.65 (56.02,63.31)
6 1804 1005 55.71 2.34 (53.37,58.05)
7 1063 533 50.14 3.07 (47.07,53.21)
8 934 521 55.78 3.25 (52.53,59.03)
9 1027 698 67.96 2.91 (65.05,70.88)
10 827 468 56.59 3.45 (53.14,60.04)
11 2403 1372 57.10 2.02 (55.08,59.11)
total 11062 6165 55.73 0.95 (54.79,56.68)