Internet Exercises

Changing the "Look" of Histograms

Shodor Education Foundation

http://www.shodor.org/interactivate/activities/histogram/index.html

The histogram evolved because there was a need to evaluate data that occurs at a certain frequency. Because the histogram allows for a concise portrayal of information in a bar graph format, it is important to see how the graphical representation can change as scales along the axes vary.

Use the histogram applet, developed by the Shodor Education Foundation, to see the graphical changes that occur when the intervals along the abscissa vary.


1		Select "College SAT Math Scores" in the box at the top of the screen and click "update histogram." The histogram will be drawn. Now change the interval size along the abscissa by clicking on the bar (it slides back and forth) just above the "update histogram" button. What happens to the "look" of the histogram when you make adjustments to the interval width? What happens to the scale along the ordinate?



2		Try it again, but this time use the "Body Fat % of 252 Men" data. Set the interval size at 2.85 first and then change it to 18.05. Examine the differences between the two histograms. What are the major differences in the visual representations of the data? What information is "hidden" when the histogram is drawn with a larger interval size?

Critique the Graphs

C. J. Schwarz, Simon Fraser University.

http://www.stat.sfu.ca/~cschwarz/Stat-301/Handouts/node8.html


3		Review these graphs and the flaws discussed. What corrections should be made to the "Job Security" pie chart? Identify one major flaw on the "Sales of Seafood." graph.

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