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Exercise 9.2

1.
To investigate the robustness of the three point estimates, consider the following data set:
      X   12 15 18
      Y   16 19 25 28
(a)
Obtain the three estimates: median of differences, difference in means, difference in medians. (Answers: 7, 7, 7).
(b)
Next replace the Y observation 28 by 2800. Obtain the three estimates: median of differences, difference in means, difference in medians. (Answers: 7, 700, 7).
2.
We will use the next two problems to investigate the robustness of the confidence intervals.
(a)
Obtain comparison dotplots of the following data:
            X:
                31    32    33    37    37    44    44    45    45    46    50    50    50 
                57    57    58    59    59    67    67

            Y:
                40    45    45    47    50    52    53    53    54    54    55    61    63 
                66    67    68    73    73    76    83
(b)
Using Class code,  Two-Sample Hypothesis and CI (Wilcoxon), obtain the estimate of $\Delta$ and the confidence interval for it using the Wilcoxon.
(c)
Using Class code,  Two-Sample Hypothesis and CI (mean), obtain the estimate of $\Delta$ and the confidence interval for it using the difference in means.
(d)
Using Class code,  Two-Sample Hypothesis and CI (median), obtain the estimate of $\Delta$ and the confidence interval for it using the difference in medians.
(e)
Compare the intervals.
3.
Consider the samples (same as last problem but the typo of 67 on the last data point of the X's was discovered and its true value of 670 has been put in):
      X:
          31    32    33    37    37    44    44    45    45    46    50    50    50 
          57    57    58    59    59    67    670

      Y:
          40    45    45    47    50    52    53    53    54    54    55    61    63 
          66    67    68    73    73    76    83
(a)
Using Class code,  Two-Sample Hypothesis and CI (Wilcoxon), obtain the estimate of $\Delta$ and the confidence interval for it using the Wilcoxon.
(b)
Using Class code,  Two-Sample Hypothesis and CI (mean), obtain the estimate of $\Delta$ and the confidence interval for it using the difference in means.
(c)
Using Class code,  Two-Sample Hypothesis and CI (median), obtain the estimate of $\Delta$ and the confidence interval for it using the difference in medians.
(d)
Compare the intervals.

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Next:Exercise 9.3 Up:No Title Previous:Exercise 9.1

2000-08-26