patients, all of whom were treated with radiotherapy, were followed
from the first day of their treatment until recurrence of the original
tumor. Recurrence is defined as the reappearance of a metastasis in
exactly the same site, or in the case of patients whose tumor never com-
pletely disappeared, enlargement of the original lesion. Times to recur-
rence (in weeks) for the 23 patients were: 2, 2, 2, 3, 4, 5, 5, 6, 7, 8, 9, 10,
14, 14, 18, 19, 20, 22, 22, 31, 33, 39, and 195. Calculate the mean, geo-
metric mean, and median.2.24 A laboratory investigator interested in the relationship between diet and
the development of tumors divided 90 rats into three groups and fed
them with low-fat, saturated-fat, and unsaturated-fat diets, respectively.
The rats were all the same age and species and were in similar physical
condition. An identical amount of tumor cells was injected into a foot
pad of each rat. The tumor-free time is the time from injection of tumor
cells to the time that a tumor develops. All 30 rats in the unsaturated-fat
diet group developed tumors; tumor-free times (in days) were: 112, 68,
84, 109, 153, 143, 60, 70, 98, 164, 63, 63, 77, 91, 91, 66, 70, 77, 63, 66,
66, 94, 101, 105, 108, 112, 115, 126, 161, and 178. Calculate the mean,
geometric mean, and median.
2.25 The Data shown in Table E2.25 are from a study that compares adoles-
cents who have bulimia to healthy adolescents with similar body com-
positions and levels of physical activity. The table provides measures of
daily caloric intake (kcal/kg) for random samples of 23 bulimic adoles-
cents and 15 healthy ones.
TABLE E2.25
Bulimic Adolescents Healthy Adolescents
15.9 17.0 18.9 30.6 40.8
16.0 17.6 19.6 25.7 37.4
16.5 28.7 21.5 25.3 37.1
18.9 28.0 24.1 24.5 30.6
18.4 25.6 23.6 20.7 33.2
18.1 25.2 22.9 22.4 33.7
30.9 25.1 21.6 23.1 36.6
29.2 24.5 23.8(a)Calculate and compare the means.
(b)Calculate and compare the variances.2.26 Two drugs, amantadine (A) and rimantadine (R), are being studied for
use in combating the influenza virus. A single 100-mg dose is adminis-
tered orally to healthy adults. The response variable is the time (minutes)
required to reach maximum concentration. Results are shown in Table
E2.26.
100 DESCRIPTIVE METHODS FOR CONTINUOUS DATA