Exercise 1.5

1.

Use the summary module to obtain these statistics for the two data sets in #1, Exercise 1.4. Using these statistics, obtain comparison boxplots of the two samples.

2.

Check the robustness of the statistics in the descriptive statistics command on the following two data sets using the summary module.

 
Data1  Data2
102   1020
131    131
137    137
 63     63
 42     42
 12     12
 23     23
 49     49
 63     63
 21     21
 56     56
 68     68
 35     35
 63     63
 62     62
 19     19
 85     85
 38     38
 76     76
 29     29
 31     31
 16     16
  0      0
  8      8
 47     47
 40     40
  2      2
 44     44
  8      8
 16     16
  7      7
 43     43
  2      2
 50     50
 22     22
  1      1
 51     51
 34     34
  4      4
 78     78
 

Notice that in the second data set,the 102 was changed to 1020. Which statistics were robust to this change? Which weren't?

3.

Same as the last exercise but change the 1020 to 10200.

4.

Same as the last exercise but change the 10200 to 102000.

5.

Did Manuel I shortchange the people by having less silver in in later days mintings? Try to answer this question by comparing the following two data sets (use comparison boxplots). The first data set is the amount of silver (percentage)in Manuel's first minting while the second data set is the amount of silver (percentage) in Manuel's fourth minting.

 
Silver Minting
5.9        1
6.8        1
6.4        1
7.0        1
6.6        1
7.7        1
7.2        1
6.9        1
6.2        1
5.3        4
5.6        4
5.5        4
5.1        4
6.2        4
5.8        4
5.8        4
 

6.

Using the LDL levels of quail a drug compound (call it A) was put on test. In the experiment, 30 quail were randomly chosen and 20 were assigned to a placebo and the other 10 to the treatment using Drug A. The drug was mixed in their food. Other than this, though, the quail were treated the same. At the end of the treament period, the Low Density Lipid levels of the quail were measured and are given below. Here smaller is definitely better. The data are real.(drug=0 for placebo and drug=1 for drug A)

LDL drug
 64    0
 49    0
 54    0
 64    0
 97    0
 66    0
 76    0
 44    0
 71    0
 89    0
 70    0
 72    0
 71    0
 55    0
 60    0
 62    0
 46    0
 77    0
 86    0
 71    0
 40    1
 31    1
 50    1
 48    1
152    1
 44    1
 74    1
 38    1
 81    1
 64    1

(a)

Obtain comparison dot plots of the data and try to decide if the drug A was effective.

(b)

Obtain the descriptive statistics for each data sets. Which (difference in means, difference in medians, difference in HL) seem more appropriate here? Why?

2000-08-26