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. Name at least one confounding variable – that could be included in this experiment as a blocking factor - can exist to debate the validity of the findings.

Answer 1

Solution :

Confounding variable : A confounding variable is a outer influence that can influence the outcome of an experimental design. In other words confounding variables are the variables that are not used in the experiment but can affect the outcome of the experiment.

Now in the given experiment there are some confounding variables which should be taken care of. One such variable is health condition of students. It may be that the health condition of all the students are not same. Some of them may have relatively weak immune system than others. So health condition of students could be included as blocking factor. One other confounding variable can be gender of students. The blocking could have been done on the basis of the gender of the students.