It is very common to find a chart relating to index numbers so drawn that the chart does not extend to the zero of the vertical scale. Such a chart may give a false impression of much more violent fluctuation than would be interpreted from a chart plotted on the usual co-ordinate field and showing the zero of the vertical scale.

Fig. 92 is taken from the United States Government Croj) Reporter, a magazine widely distributed to farmers.

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Fig. 92. Fluctuation in the Price of Eggs in the United States as Compared with the Average of the Monthly Figures for the Preceding Four Years

An untrained reader may not realize that this chart must be read from the line representing 100 per cent. Charts for index numbers, where the fluctuation is compared with 100 per cent, should have the 100 per cent line made broad, and a wavy line should be used at the bottom of the chart unless the zero of the scale is shown. An alternative arrangement is shown in Fig. 93

It has been the hope of this magazine to give producers of agricultural products an opportunity to study the price records of previous years, so that they may, in so far as possible, sell at the time of the year when prices are the highest. It is much to be doubted whether the average reader of charts like that seen in Fig. 92 would realize that the 100 per cent line must be used as a basis for interpreting the chart.