A1-TimothyWheeler

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Good Example

Image:tw_a1_airfoil.jpg

In these photographs, water flows from left to right. Dye is injected upstream (on the left) from evenly spaced nozzles. The resulting streamlines provide a visualization of the complex phenomena that occur in fluid mechanics. Some noteworthy features:

  • In (b), the interesting phenomena are labeled on the graphic itself.
  • The use of small multiples invites comparison between (a) and (b).

This figure was taken from [1] (see References below).

Bad Example

Image:tw_a1_stats.jpg

This graphic is meant to illustrate the concepts of mean, median, and mode for a skewed data set. The author hopes to use a lever-and-fulcrum analogy to show how outliers influence the mean. However, by using inconsistent spacing on the horizontal axis, the illustrator failed to capture the spatial relationship between points that are near the fulcrum and those that are far away. (From 15 to 50, the spacing is about 5.7 units/cm. From 50 to 70, the spacing is about 11 units/cm. From 70 to 90, the spacing is about 10 units/cm. Of course, the illustrator has denoted large gaps between 70, 475, and 710 units.) Also, with a data point "sitting" at the mean, the graphic seems to imply that the mean must coincide with a data point. This implication is potentially confusing in such an elementary discussion of statistics.

This figure was taken from [2] (see References below).

References

  1. B.R. Munson, D.F. Young, and T.H. Okiishi, Fundamentals of Fluid Mechanics, New York: John Wiley & Sons, 2002, p. 571.
  2. D. Myers, Psychology, 7th ed., New York: Worth Publishers, 2004, p. 43.


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