Question

Explain what is wrong with each of the following randomization procedures, and describe how you would do the randomization correctly.

a. Twenty students are to be used to evaluate a new treatment. Ten men are assigned to receive the treatment, and 10 women are assigned to be the controls.
b. Ten subjects are to be assigned to two treatments, 5 to each. For each subject, a coin is tossed. If the coin comes up heads, the subject is assigned to the first treatment: if the coin comes up tails, the subject is assigned to the second treatment.
c. An experiment will assign 40 rats to four different treatment conditions. The rats arrive from the supplier in batches of 10, and the treatment lasts two weeks. The first batch of 10 rats is randomly assigned to one of the four treatments, and data for these rats are collected. After a one-week break, another batch of 10 rats arrives and is assigned to one of the three remaining treatments. The process continues until the last batch of rats is given the treatment that has not been assigned to the three previous batches.

Answer 1

Kindly check explanation

Explanation:

A.)

The problem with the here is that we might have introduced bias into our sample by failing to randomize the assignment of gender. By pacing the male gender in the treatment group and females into the control group, this might spring up a spurious association in our experiment as a result of a possible confounding variable, gender. Therefore, assignment of subject shouldn't be on the basis of gender.

2.)

Using a coin toss in placing subjects into groups will give a good random assignment, however, since only ten subjects are available and of which 5 will be placed into each group, there is no certainty that there will be equal number of heads and tails during the 10 flips. Alternatively, a random selection of the name of the 10 subjects could be chosen from a raffle.

3.)

Each batch of rat might be homogenous and hence will affect our experiment and definitely our conclusion. It would be best to assign rats from each batch to all treatment groups in other to obtain a good random design