Question

The Schiffert Health Center at Virginia Tech wants to see whether putting antibacterial soap in the dormitory bathrooms will reduce the number of visits to the infirmary. VT has 47 on-campus residence halls. They are home for 9300 students. Twenty residence halls have been randomly selected. In all 2,000 students spanning over all selected halls. Half of the dormitories are chosen at random and supplied with the special soap; the remaining ones were supplied with regular soap. At the end of the semester, the two types of soap are compared using the number of visits to the infirmary per person per semester.

1. We have studied two types of designs (complete randomized design and complete randomized block design). According to this scenario above, what type is this design?

Answer 1

Solution: According to the scenario that is given in the question, the type of design is "Complete randomized design". In complete randomized design we allocate the treatments to the experimental unit in pure random manner, so that every unit has an equal chance of getting the treatments. In CRD also we do replication of the treatments. Complete randomized design is used for homogeneous experimental fields. In our question there are two treatments one is "special soap" and other is "regular soap". Out of total dormitories half of the dormitories are selected randomly and supplied with the special soap and remaining dormitories are supplied with the regular soap. It shows that treatments are allocated to the experimental unit completely at random. In the given scenario experimental units are not divided into homogeneous subgroups known as block. So, the type of design is not complete randomized block design.

All the informations that is given in the scenario matches with the characteristics of complete randomized design. Hence in the given scenario the type of design is "complete randomized design".