Data are shown in Table E2.27 for two groups of patients who died of acute myelogenous leukemia. Patients were classified into the two groups according to the presence or absence of a morphologic characteristic of white cells. Patients termed AG positive were identified by the presence of Auer rods and/or significant granulature of the leukemic cells in the bone marrow at diagnosis. For AG-negative patients, these factors were absent. Leukemia is a cancer characterized by an overproliferation of white blood cells; the higher the white blood count (WBC), the more severe the disease.
|
AG Positive, N = 17
Survival Time
WBC (weeks)
|
AG Negative, N = 16
Survival Time
WBC (weeks)
|
|
2,300 65
|
4,400
|
56
|
|
750 156
|
3,000
|
65
|
|
4,300 100
|
4,000
|
17
|
|
2,600 134
|
1,500
|
7
|
|
6,000 16
|
9,000
|
16
|
|
10,500 108
|
5,300
|
22
|
|
10,000 121
|
10,000
|
3
|
|
17,000 4
|
19,000
|
4
|
|
5,400 39
|
27,000
|
2
|
|
7,000 143
|
28,000
|
3
|
|
9,400 56
|
31,000
|
8
|
|
32,000 26
|
26,000
|
4
|
|
35,000 22
|
21,000
|
3
|
|
100,000 1
|
79,000
|
30
|
|
100,000 1
|
100,000
|
4
|
|
52,000 5
|
100,000
|
43
|
|
100,000 65
|
(a) Calculate separately for each group (AG positive and AG negative) the mean x, variance s2, and standard deviation s for survival time.
(b) Calculate separately for each group (AG positive and AG negative) the mean, geometric mean, and median for white blood count.