Experiments
The drug AZT was the first effective treatment for AIDS. An important medical experiment
demonstrated that regular doses of AZT delay the onset of symptoms in people whom
HIV is present. The researchers who carried out this experiment wanted to know the following:
* Does taking either 500 mg of AZT or 1500 mg of AZT per day delay the development
of AIDS?
* Is there any difference between the effects of taking these two doses?
The subjects were 1200 volunteers already infected with HIV but with no symptoms of AIDS
when the study started.
a) Outline the design of the experiment
b) Describe briefly how you would use a table of random digits to do the randomization required
by design. Then use Table B beginning at line 113 to choose the first five subjects for one of
your groups.
a) The design of the experiment would involve randomizing the subjects into two groups: a group that takes 500 mg of AZT per day and a group that takes 1500 mg of AZT per day. This randomization ensures that any differences observed in the effects of the two doses can be attributed to the dose itself and not other factors.
To implement this design, the researchers would first recruit the 1200 volunteers already infected with HIV but without symptoms of AIDS. They would then randomly assign each volunteer to either the 500 mg group or the 1500 mg group. To ensure the groups are balanced, the randomization process must be unbiased and done in a way that each volunteer has an equal chance of being assigned to either group.
b) To use a table of random digits for randomization, the researchers would assign each volunteer a number, from 1 to 1200. They would then use the table to generate random numbers between 1 and 1200. Starting at line 113 on Table B, they would read the numbers row by row until they have selected five numbers. These five numbers would correspond to the five subjects chosen for one of the groups.
For example, let's say the first five numbers generated are 731, 586, 929, 201, and 315. The researchers would assign the volunteers with these corresponding numbers to the same group, either the 500 mg or the 1500 mg group.
It is important to note that this process should be repeated until all 1200 volunteers have been randomly assigned to one of the two groups. Each volunteer should be assigned only once, and the randomization should be done in a way that prevents any systematic bias or patterns in the assignment. The use of a table of random digits helps achieve this randomization.