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A study is designed to determine whether grades in a statistics course could be

ID: 3355393 • Letter: A

Question

A study is designed to determine whether grades in a statistics course could be improved by using a different teaching technique. The 250 students enrolled in a large introductory statistics class are also enrolled in one of 6 recitation sections. The 6 sections are randomly divided into 2 groups of 3 sections each. The students in the first set of 3 recitations are taught using this “new” method. The remaining students are taught using the current technique. The grades at the end of the term are then compared. Assume that the students do not know if the method they are being taught with is the old or the new method.

Fill in the blank. Suppose the students in the "new" group were mostly upper-classmen and the students in the "old" group were mostly first and second-year students. The variable "year in school" is an example of a(n) _________ variable.

Explanation / Answer

Confounding variable: extra variables that have a hidden effect on your experimental results. As the presence of upper-classmen in the new group would help the group perform due to the experience of upper-classmen.