Justification:

The conditions for the population and the study design that are required by the procedure and are used to construct the confidence interval is,

- Simple random sample from the population.

- Observations are from a normal population.

The important condition is that, the 27 members of the placebo group tested which is considered as simple random sample from a population. Thus, the most important condition for their safe use is that the data can be regarded as an SRS from the population because the t procedures are robust.

The conditions for the population and the study design that are required by the procedure and are used to construct the confidence interval is,

- Simple random sample from the population.

- Observations are from a normal population.

The important condition is that, the 27 members of the placebo group tested which is considered as simple random sample from a population. Thus, the most important condition for their safe use is that the data can be regarded as an SRS from the population because the t procedures are robust.