Introduction to Frequency Graphs for One Quantitative Variable

The point is to learn how to "pile up" values that are close together to provide a two-dimensional picture of the data. This is the key idea on which much of the whole discipline of statistics is based. For now, just watch these four, in sequence. We go from graphing points on a number line to "piling up" points so it is easier to see how much data is "close together."

• Use an individual value plot to remind you of putting points on a number line (from your elementary math classes.)
• Use a dotplot to see how the values "pile up" to form a frequency graph
• Histograms are generalizations of dotplots, where you "pile up" nearby data values by taking intervals of values to make a bar.
• Stemplots are sometimes used as a quick way of organizing the numbers.
  

Go here to use visualize applets to explore each of these in much more detail.

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