Page:Graphic methods for presenting facts (1914).djvu/95

In Fig. 70 vertical bars have been placed touching each other, with the earlier years at the right. The whole arrangement of the chart is extremely poor and also misleading. In Fig. 71 the data of Fig. 70 have been replotted. The most striking thing about Fig. 71 is the falling off in the rate of increase of production in the decade between 1870 and 1880. The shape of the curve at once starts a train of thought in regard to tariff legislation and other conditions which may affect the manufacture of cotton goods.

It will be noticed in Fig. 71 that we have four curves, while only three sets of bars were given in Fig. 70. It is evident that if we add production and imports and then deduct exports, we will have a fair indication of consumption if the amounts remaining in warehouses, etc. (which are probably a negligible percentage of the whole consumption) are excepted. Note that the import and export curves follow each other in general form, though the export curve fluctuates on a percentage basis much more rapidly than does the import curve. Remember that in the fluctuations of two curves like these, the change from year to year must be judged from the zero base line rather than from the slope of the curves themselves. The drop in the export line from 1860 to 1870 was almost one-half, while the drop in the import line for the same period was much less than one-half, even though the import line does show the greater slope downward.

Fig. 71. Cotton Goods Production, Import and Export for the United States

These curves are plotted from the data of Fig. 70, and show the information in much clearer form

In Fig. 72 we have an example of what not to do in charting. The main effect of the circles is to give one a headache without permitting any accurate comparison between the years. The eye does not easily see each circle as an area. The tendency is to see only rings