Identify the independent variable, dependent variable, and the null hypothesis from the following scenario:

Question

A researcher would like to know if highlighting a textbook helps students to score better on the exams. She
randomly selects one-half of the students in an introductory class and instructs them to highlight their textbooks as
they read. The other students are instructed to do NO highlighting as they read.

Answer 1

Although the relationship between independent and dependent variables is NOT always a cause-and-effect relationship, try to think of a cause-and-effect that is in this scenario to help you identify the variables, where your independent variable (IV) is the "cause" and the dependent variable (DV) is the "effect."

 

In this case, highlighting the textbook is the "cause"-like variable, and is your IV. It is the variable that is being tested, and is not caused by/does not depend on any other variables.

 

The students' scores are the "effects" in this scenario and are you DVs; they are dependent on whether or not the students highlight in their books.

 

The null hypothesis is simply that there is no correlation between your variables; in this case it's the idea that highlighting does not help the students score better, and that there isn't a difference between your two groups.