Page:Graphic methods for presenting facts (1914).djvu/330

 with many of the charts, there is danger of misinterpretation. For instance, it is not at all easy to analyze Fig. 220 so that its four different subjects may be compared.

Fig. 220. Percentage Increase in Freight Service on the Illinois Central Railroad Since 1902. This Illustration Was Taken from the 1912 Annual Report of the Company

Four distinct subjects are treated in this chart, but the horizontal bars are arranged in such manner that the reader is likely to think there is only one subject. Probably most readers would prefer to turn the chart so that it may be read from the left-hand edge as four separate curves. To a trained reader this information would be much more clear if put in the form of curves like those seen in Figs. 224, 225, 226, 227

Fig. 221 also shows several different subjects which should be compared, but for which comparison is not very feasible on the chart as given. In Fig. 220 the four different subjects were so widely separated that comparisons were almost impossible, while in Fig. 221 the four different subjects have the bars so arranged that it is difficult for the eye to follow any one subject through the maze of bars.

In Fig. 222 the method of presentation is somewhat similar to that used in Fig. 221. As seen in Fig. 222, however, the bars are