Duncan et all. (2012) report a study which explores the effect on course grade of cell phone use dun'ng class. As part of the study, students in ve University of Colorado Astronomy classes selfreported their cell phone usage per one hour class. Students were then classied by their cell phone use into four groups: Never, 12, 34, and >5 times per class. The grades of the students were recorded on a four point scale with an 'A' being 4.0. Suppose the grades from one of the ve classes were as tabulated below: Course grade by reported frequency of cell phone use Never 1-2 times 3-5 times >5 times 2.6 3.6 2.8 3.3 1.6 2.5 2.9 2.7 2.8 4.5 3.7 2.9 2.2 2.4 3.6 2.2 2.3 Duncan, D., Hoekstra. A. and Wilcox, E. (2012): Digital devices. distraction, and student performance: does inclass cell phone use reduce learning? Astronomy Education Re view 11, 0101061, 10. 384YIAER201 2 Part a) In the article, the authors display their data using a plot of means with error bars. Which of the following would have been a preferable method? 0 A. Four stemandIeaf plots (9 B. Sidebyside boxplots Q C. A pie chart 0 D. Four histograms plotted on the same axis 0 E. A histogram Part b) Which of the following hypotheses could reasonably be tested by the data presented in the study? 0A. In the population of students who take an Astronomy class at the University of Colorado, if placed into four groups determined by their cell phone use in class as above, the variances of the course grades are equal. 0 B. In the four groups of students determined by their cell phone use in class, the sample means of the course grades are equal. 0 C. In the four groups of students determined by their cell phone use in class, the sample variances of the course grades are equal. (9 D. In the population of students who take an Astronomy class at the University of Colorado, if placed into four groups determined by their cell phone use in class as above, the means of the course grades are equal. 0 E. There is no correlation between course grade and the number of times students use their cell phone in class. Part c) Perform a suitable nonparametric test in R on the data above. Provide the value of your test statistic to two decimal places. Part d) Under the null hypothesis, the statistic should be an observation from which probability distribution? 0A. The Chisquared distribution on two degrees of freedom. 0 B. The standard Normal distribution. 0 C. The t distribution on two degrees of freedom. (9 D. The Chisquared distribution on three degrees of freedom. 0 E. The Chisquared distribution on four degrees of freedom. 0 F. The F9535 distribution. Part e) Would you reject or not reject your null hypothesis at the 5 % signicance level? @A. Not reject Q B. Reject