Page:Graphic methods for presenting facts (1914).djvu/89



CURVE PLOTTING

Information may be charted in many different ways. Under present conditions, if six men were given a set of figures and asked to chart these figures, the six resulting charts would be widely divergent in method. Though variety in method of charting is sometimes desirable in large reports where numerous illustrations must follow each other closely, or in wall exhibits where there must be a great number of charts in rapid sequence, it is better in general to use a variety of effects simply to attract attention, and to present the data themselves according to standard well-known methods.

In Fig. 66 the attempt to give a spectacular scheme of presentation seems to have overshadowed everything else in the mind of the illustrator. Though a striking architectural design has undoubtedly been obtained, the chart means nothing, for it is impossible of interpretation. No scale has been used in either the horizontal or the vertical direction, as can be seen by comparing the figures on the block for 1830 with the figures on the block for 1840. Even if some scale had been used in making up this chart, the general scheme is such that the reader would hopelessly flounder in trying to reach an accurate interpretation.

Fig. 67 puts the data given in Fig. 66 in the form of horizontal bars. Note that the values which the bars represent are given inside of the bars, for reference purposes. In order to make the shape of each bar stand out distinctly, gray dots were used which permit the figures representing the values to be read through the shading. This is an interesting attempt, but it is not satisfactory as a general scheme. Though Fig. 67 gives the data much more clearly and far more accurately than Fig. 66, the method is not satisfactory because it is difficult for the eye to follow the ends of the different bars in order to judge the increase made from decade to decade. The best method