Chapter 5.1, Problem 11E

The paper “The Relationship Between Cell Phone Use, Academic Performance, Anxiety, and Satisfaction with Life in College Students” (Computers in Human Behavior [2014]: 343-350) described a study of cell phone use among undergraduate college students at a public university. The paper reported that the value of the correlation coefficient between x = Cell phone use (measured as total amount of time in hours spent using a cell phone on a typical day) and y = GPA (cumulative GPA determined from university records) was r = −0.203.

1. a. Interpret the given value of the correlation coefficient. Does the value of the correlation coefficient suggest that students who use a cell phone for more hours per day tend to have higher GPAs or lower GPAs?
2. b. The study also investigated the correlation between texting (measured as the total number of texts sent and texts received per day) and GPA. The direction of the relationship between texting and GPA was the same as the direction of the relationship between cell phone use and GPA, but the relationship between texting and GPA was not as strong. Which of the following possible values for the correlation coefficient between texting and GPA could have been the one observed?

   $r=-0.30r=-0.10r=0.10r=0.30$

3. c. The paper included the following statement: “Participants filled in two blanks-one for texts sent and one for texts received. These two texting items were nearly perfectly correlated.” Do you think that the value of the correlation coefficient for texts sent and texts received was close to −1, close to 0, or close to +1? Explain your reasoning.