Exercise 9.3

1.

If you didn't do it, use class code to obtain a 95% confidence interval for the true difference in proportions for the above example of the two different drugs.

2.

Should the president be worried? Polls of wealthy financial backers before and after she made a controversial decision were tabulated and given to her. What do you think? Base your answer on a 95% confidence interval.

                        Will Contribute   Will Not
      Before Decision        68              13
      After Decision         38              20

3.

In the example of the two different drugs found above, the sorted resampled differences in proportions were given. Here's a dot plot of them. Locate the estimate and the confidence interval on it.

      
                                   :
                                   :     : : . :
                                   : : : : : : :   :   .
                                 : : : : : : :.:.. :   : .
                   . . : ..     .: :.: :.:.:.:::::.: . :.:. .. . .      .
                +---------+---------+---------+---------+---------+-------C1      
            -0.50     -0.40     -0.30     -0.20     -0.10      0.00