Suppose you obtain and read information about new pain medications. A study was conducted to test the side effects of two drugs for the pain medications. TABLE 1 shows the results from the study.
TABLE 1
|
Side effect
|
Number of side effects in 12-week clinical trial
|
|
Placebo
n = 192
|
Drug A
n = 186
|
Drug B
n = 188
|
|
Upper respiratory congestion
|
10
|
32
|
19
|
|
Sinus headache
|
11
|
25
|
32
|
|
Stomach ache
|
2
|
46
|
12
|
|
Neurological headache
|
34
|
55
|
72
|
|
Cough
|
22
|
18
|
31
|
|
Lower respiratory congestion
|
2
|
5
|
1
|
|
None
|
111
|
3
|
21
|
a) State whether the study is observational or experimental. Explain your reason.
b) List all the variables.
c) A person is selected at random. Find the probability that the person was
i. receiving a placebo.
ii. receiving drug A or B. Are these events mutually exclusive? Give the reason.
iii. not receiving a placebo or experienced a sinus headache.
iv. having a lower respiratory congestion given that he or she received drug A.
d) Four (4) persons are selected at random for interview session. Two (2) persons from those who received drug A, and the others from those who received drug B. Is it unusual that all of them did not having any side effects? Justify your answer.