Serum estradiol is an important risk factor for breast cancer in postmenopausal women. To better understand the etiology of breast cancer, serum-estradiol samples were collected from 25 premenopausal women (at about the same time period of the menstrual cycle) of whom 10 were Caucasian and 15 were African American. The data are shown in Table 7.3. The distribution of serum estradiol is usually highly skewed (especially for premenopausal women), and we are reluctant to assume normality. Table 7.3 Serum estradiol and ethnicity in 25 premenopausal women, where 0=Caucasian and 1=African-American ID Serum_estradiol Ethic 1 94 0 2 54 1 3 31 0 4 21 1 5 46 1 6 56 0 7 18 1 8 19 1 9 12 1 10 14 0 11 25 0 12 35 1 13 22 1 14 71 0 15 43 1 16 35 1 17 42 1 18 50 1 19 44 1 20 41 0 21 28 0 22 65 0 23 31 0 24 35 1 25 91 1 7.1: What test can we use (Sign test, or Wilcoxon signed-rank test or Wilcoxon rank-sum test) to compare the distribution of serum estradiol for Caucasian vs. African American women? Implement the test in Problem 7.1, and report a two-tailed p-value based on large sample methods.
Serum estradiol is an important risk factor for breast cancer in postmenopausal women. To better understand the etiology of breast cancer, serum-estradiol samples were collected from 25 premenopausal women (at about the same time period of the menstrual cycle) of whom 10 were Caucasian and 15 were African American. The data are shown in Table 7.3. The distribution of serum estradiol is usually highly skewed (especially for premenopausal women), and we are reluctant to assume normality.
Table 7.3 Serum estradiol and ethnicity in 25 premenopausal women, where 0=Caucasian and 1=African-American
ID |
Serum_estradiol |
Ethic |
1 |
94 |
0 |
2 |
54 |
1 |
3 |
31 |
0 |
4 |
21 |
1 |
5 |
46 |
1 |
6 |
56 |
0 |
7 |
18 |
1 |
8 |
19 |
1 |
9 |
12 |
1 |
10 |
14 |
0 |
11 |
25 |
0 |
12 |
35 |
1 |
13 |
22 |
1 |
14 |
71 |
0 |
15 |
43 |
1 |
16 |
35 |
1 |
17 |
42 |
1 |
18 |
50 |
1 |
19 |
44 |
1 |
20 |
41 |
0 |
21 |
28 |
0 |
22 |
65 |
0 |
23 |
31 |
0 |
24 |
35 |
1 |
25 |
91 |
1 |
- 7.1: What test can we use (Sign test, or Wilcoxon signed-rank test or Wilcoxon rank-sum test) to compare the distribution of serum estradiol for Caucasian vs. African American women?
- Implement the test in Problem 7.1, and report a two-tailed p-value based on large sample methods.
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