Visualizing Fuel Efficiency Differences in R

For my visualization, I used the built-in mtcars dataset to compare how fuel efficiency (MPG) differs by the number of cylinders. I created a deviation chart showing how each group’s average MPG varies from the overall mean of 20.09. The chart clearly reveals that four-cylinder cars perform well above the average, six-cylinder cars fall slightly below, and eight-cylinder cars are far below the mean. This visualization highlights clear differences between groups and how engine size affects fuel efficiency.

This chart aligns with Few’s (Chapter 9) principles of simplicity and comparison by using a clean design and a baseline to emphasize differences from a meaningful average. It also follows Yau’s (Chapter 7) idea that the best charts fit the question being asked—here, a deviation chart clearly illustrates variation from a norm. My main challenge was deciding how to best show the deviation; once I used the dashed reference line, the differences became much easier to interpret.