Graphic Methods for Presenting Facts
the graphic method of stepping off the height for the total curve is practically the only one available. After each of the separate curves has been plotted from such data as may exist, it is a very simple matter by the graphic method to locate the total curve from the separate curves. A sufficient number of vertical lines are used to bring the points on the total curve close enough together to represent fairly the data of the separate curves which are totaled.
In plotting curves relating to prices, it frequently happens that there is a necessity for showing in the chart both the upper and lower limits to which the prices may fluctuate in any given period of time.
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Adapted from Pennsylvania Farmer
Fig. 114. Chart to Show the Dependence of Com Yield upon the Quantity of Rainfall during the Month of July. The Yield of Corn is Given in Bushels per Acre
This chart is misleading. The close similarity of the two curves has been obtained by plotting one curve on a larger scale than that used for the other curve. The rainfall curve has been plotted with the bottom of the chart as zero. The corn-yield curve is, however, drawn with the scale starting at twelve.