Comparing Randomly Allocated Groups
Cibsuder a study to compare two antiobiotics for
treating strep throat in children, amoxicillin and
cefadroxil. At one clinic for this study, 23 children
(who met the study entrance criteria and for whom consent
was given) were randomly allocated into one of the two
treatment groups. One concern is that age of the child
might influence the effectiveness of the antibiotics. The
ages of the children in each treatment group are given.
Row Age Group
1 14 AMOX
2 17 AMOX
3 11 AMOX
4 10 AMOX
5 11 AMOX
6 14 AMOX
7 9 AMOX
8 12 AMOX
9 8 AMOX
10 10 AMOX
11 9 AMOX
12 9 CEFA
13 14 CEFA
14 8 CEFA
15 10 CEFA
16 13 CEFA
17 7 CEFA
18 9 CEFA
19 11 CEFA
20 16 CEFA
21 10 CEFA
22 12 CEFA
23 9 CEFA
Calculate the mean and median for each of the two
groups.
For the AMOX group the mean is
(14 + 17 + 11 + 10 + 11 + 14 + 9 + 12 + 8 + 10
+ 9)/1 = 11.364
For the CEFA group the mean is
(9 + 14 + 8 + 10 + 13 + 7 + 9 + 11 + 16 + 10 +
12 + 9)/12 = 10.667
To obtain medians the two sets of data must be
sorted. The median is then found in the center
position.
For the AMOX group the median is 11
8 9 9 10 10 11
11 12 14 14 17
For the CEFA group the median is 10.
7 8 9 9 9 10 10
11 12 13 14 16
How do the two groups compare with respect to age?
They are quite similar  at least via these
measures.
Minitab (Computergenerated) Results
Descriptive Statistics
Variable Group N Mean Median TrMean StDev
Age AMOX 11 11.364 11.000 11.111 2.693
CEFA 12 10.667 10.000 10.500 2.640
Variable Group SE Mean Minimum Maximum Q1 Q3
Age AMOX 0.812 8.000 17.000 9.000 14.000
CEFA 0.762 7.000 16.000 9.000 12.750
