Stats 244 Lab Assignment 2 - Solutions ∑ ∑ ∑ ∑ ∑ ∑

Drug A
Drug B
Drug C
Stats 244 Lab Assignment 2 - Solutions
For each of the three drugs A, B and C
a) Compute the mean and the standard deviation.
x =
x =
x =
n
∑
i=
1
n
n
∑
i=
1
n
x
x
i
i
209.
2
= = 10.
46 , s =
20
296.
0
= = 14.
80 , s =
20
n
∑ xi
i=
1 =
n
216.
6
=
20
10.
83 , s =
n
∑
i=
1
n
∑
i=
1
i=
1
n
⎛ ⎞
⎜∑
xi
⎟
2 ⎝ i=
1 x − ⎠
i n
n −1
x
2
i
2
i
⎛
⎜
− ⎝
⎛
⎜
− ⎝
n
∑
i=
1
n −1
i=
1
Page 1
x
2
2
⎞
⎟
⎠
i
n −1
b) Compute the median and the upper and lower quartiles.
The data arranged in increasing order is as follows
Drug A Drug B Drug C
4.8 7.2 3
5.9 7.4 3.1
6.1 9.3 3.1
6.4 9.9 3.4
Q1
7.9
8.3
10.1
10.1
4.4
5.2
8.6 10.7 6.2
8.9 12.4 7.2
8.9 12.8 8.8
Q2
9.4
9.4
14.6
15.2
10.2
11.1
11.5 15.5 11.2
12 15.5 12.2
12.1 17.7 13.6
Q3
12.5
14.3
18.2
19.4
14.8
15
14.4 20.9 15.8
15 22.5 16.5
15.5 23.2 24.4
17.3 23.4 27.4
Q1
Q2
Q3
81
9.4
13.4
10 1
14.9
18.8
48
10.65
14.9
n
∑
x
n
∑
x
2
⎞
⎟
⎠
i
n
n
=
=
=
2431.
72
4901.
66
3252.
44
−
( 209.
2)
19
−
−
2
( 296.
0)
19
2
( 216.
6)
19
2
20 =
20
=
20
=
3.
58
5.
24
6.
91

c) Draw box plots of reduction in blood pressure, X.
Reduction in BP
30
24
18
12
6
0
Box Plots
A B C
DRUG
d) Would you say that there is a difference in the reduction in blood pressure between the
three drugs A, B and C?
Conclusions:
1. Drug B gives on the average higher reduction in Blood Pressure than Drug A or
Drug C.
2. Drug A and C give approximately the same average reduction in Blood Pressure,
however the variability the reduction in Blood Pressure in is larger for C than it is for
A.
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Non-Outlier Max
Non-Outlier Min
Median; 75%
25%