CK-12 Probability and Statistics - Advanced

(Marvins-Underground-K-12) #1

2.1. Histograms and Frequency Distributions http://www.ck12.org


And here is the frequency polygon in finished form.


Frequency polygons are helpful in showing the general overall shape of a distribution of data. They can also be
useful for comparing two sets of data. Imagine how confusing two histograms would look graphed on top of each
other!


For example, we looked at the bottled water consumption of the leading countries in the year 2004 and you will work
with the data from 1999 at the end of the lesson, but it would be nice to be able to compare the two distributions
of data. A frequency polygon would help give an overall picture of how these results are similar and different. In
the following graph, the two frequency polygons are overlaid, 1999 in red, and 2004 in green. Can you see any
important differences in the way the graph is shaped?

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