In a study investigating how students use their laptop computers in class, researchers recruited 45 students at one university in the Northeast who regularly take their laptops to class. Software was installed on each of their computers that logged information on the applications the computer was running, including how long each was open and which was the primary focus on the monitor. Logs were kept over multiple lectures. On average, the students cycled through 65 active windows per lecture, with one student averaging 174 active windows per lecture! The researchers developed a rubric to distinguish productive class-related applications from distractive ones, such as email and social networking sites. For each student, they recorded the percent of active windows that were distractive and the percent of time spent on distractive windows. They found that, on average, 62% of the windows students open in class are completely unrelated to the class, and students had distracting windows open and active 42% of the time, on average. Finally, the study included a measure of how each student performed on a test of the relevant material. Not surprisingly, the study finds that the students who spent more time on distracting websites generally had lower test scores.

(a) What are the cases in this dataset? What is the sample size? Is the sample a random sample?

(b) Is this an experiment or an observational study? Explain.

(c) From the description given, what variables are recorded for each case? Identify each as categorical or quantitative.

(d) What graph(s) might we use to display the data about the number of active windows opened per lecture? What graph is most appropriate if we want to quickly determine whether the maximum value (174) is an outlier?

(e) The last sentence of the paragraph describes an association. What graph might be used to display this association? What statistic might be used to quantify it? Is it a positive or negative association?

(f) From the information given, can we conclude that students who allocate their cognitive resources to distracting sites during class get lower grades because of it? Why or why not?

(g) For the association described in part (e), what is the explanatory variable? What is the response variable?

(h) Describe the design of a study that might allow us to make the conclusion in part (f). Comment on the feasibility of conducting such a study.