A researcher designed a study to assess whether grades in a ...

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A researcher designed a study to assess whether grades in a statistics course could be improved by using a new teaching technique. The 250 students enrolled in a large introductory statistics class are also enrolled in one of 20 lab sections. The 20 lab sections are randomly divided into 2 groups of 10 lab sections each. The students in the first set of 10 lab sections are taught by this new method. The students in the remaining 10 lab sections are taught using the old techniques. 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. 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. What is the statistical name for the variable year in school in this study?

Question 2

A researcher designed a study to assess whether grades in a statistics course could be improved by using a new teaching technique. The 250 students enrolled in a large introductory statistics class are also enrolled in one of 20 lab sections. The 20 lab sections are randomly divided into 2 groups of 10 lab sections each. The students in the first set of 10 lab sections are taught by this new method. The students in the remaining 10 lab sections are taught using the old techniques. 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. Identify the explanatory variable and the response variable in this study.

[dellikani2015]

Answer to Question 1

Year in school would be a confounding variable.

Answer to Question 2

The explanatory variable is teaching method (with two levels of old versus new). The response variable is the course grade.