ISQA 521 – Spring 2020



ISQA 521 – Spring 2021Homework Week 2Short Answer QuestionsWhat is binning and why is it associated with histograms and not bar charts? Identify and describe two properties of histogram bins that lead to arbitrariness in the histogram display.What is the histogram artifact of under-smoothing and how does it relate to sample size? How can the problem be fixed?How does a frequency polygon differ from a histogram? How is the same?Why can a density plot be more representative of the underlying distribution than a histogram. What information is not provided by the density plot that is available from the histogram?From which statistics is a box plot created? What is the general characteristic of these statistics?By far, most created box plots do not adjust for symmetry. What is that concept and why is it important?Likert data consist of responses to an item on a survey that consist of a set of categories such as Strongly Disagree, etc, usually 5, 6 or 7 categories. Yet the corresponding violin chart is continuous. Reconcile these two statements. Is the violin plot appropriate?What is a Pareto chart?What does it mean to map a grouping variable to a visual aesthetic? What are some appropriate such aesthetics?What is the purpose of a confidence band around a line of best-fit through a scatterplot?How can a hierarchical cluster analysis help structure a correlation matrix?What is a smoothed scatterplot? When is it most appropriate?What is the distinction between a stacked and an unstacked bar chart?What is a 100% bar chart, and what is its primary purpose?Worked ProblemsFormat text copied from R and pasted into a word processing document as mono space, such as with the Courier New font at 9 or 10 pt.Data for analyses: . Univariate Continuousa. Provide the histogram using default bins for the city MPG. i. lessR. ii. ggplot2b. Provide the histogram with a more appropriate bin width for the city MPG. i. lessR. ii. ggplot2c. Provide the ggplot2 overlapping histograms for city MPG for USA and non-USA cars. d. Provide the side-by-side histograms (Trellis plots) for city MPG for USA and non-USA cars. i. lessR. ii. ggplot2e. Provide the density curve for city MPG. Display the entire range of the curve. i. lessR. ii. ggplot2f. Provide the overlapping density curves for city MPG for USA and non-USA cars. (either lessR or ggplot2)g. Provide the box plots that compare city MPG for USA and non-USA. (either lessR or ggplot2)h. Provide the integrated Violin/Box/Scatterplot (VBS) for city MPG. (either lessR or ggplot2)i. What are some advantages and disadvantages of the VBS plot compared to the histogram? Discuss with respect to this example.2. ScatterplotProvide the scatter plot for MPG highway and Horsepower, with the 95% confidence data ellipse.i. lessR. ii. ggplot2[for the rest of the scatterplot questions, use any function you wish]Provide the Trellis scatterplots for MPG highway and Horsepower for USA vs non-USA cars.Provide scatter plot for MPG highway and Horsepower for USA vs non-USA cars plotted on the same panel, with the corresponding regression lines. Interpret.Plot the scatterplot for MPG highway and Horsepower, mapping MidPrice to the size of each point.Show the scatterplot matrix for MidPrice, MPGcity, MPGhiway, HP, and Weight.Show the ordered heat map matrix for MidPrice, MPGcity, MPGhiway, HP, and Weight.3. Bar Chart of Two Variables: Cross-TabulationProvide the stacked bar chart for type of car by the airbag configuration (none, driver only, driver and passenger). i. lessR ii. ggplot2Provide the unstacked bar chart for type of car by the airbag configuration (none, driver only, driver and passenger). i. lessR ii. ggplot2Briefly interpret the relationship between type of car and airbag.Provide the proportional (100%) stacked bar graph for type of car and airbag configuration. (either lessR or ggplot2)Briefly interpret the 100% bar graph.Provide the bar graph that plots the MPG in the city for each type of car. (either lessR or ggplot2) ................
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