Page:Graphic methods for presenting facts (1914).djvu/68

 as decreasing 4 per cent. The scale would read upward from the zero line for increases, and downward from the zero line for decreases. By changing the scale and using a broad zero line, misinterpretation of the chart would be entirely prevented.

Reproduced by Permission from Droege's "Freight Terminals and Trains", copyright, 1912, by the McGraw-Hill Book Company

Fig. 53. Changes after Ten Years in Costs of Railroad Materials and in Freight Rates for a Large Railroad System

A simple chart of this kind is often advantageous, as it neglects all temporary fluctuations and shows only the important changes over a period of time considered as a whole. The line for 100 on the scale should have been made a broad line to indicate the basis of comparison. A wavy line should have been put at the bottom of the chart to show that the scale does not begin at zero

Fig. 54 is somewhat similar to Fig. 53 in that intervening years are neglected, and that lines drawn from left to right of the chart indicate the total movement rather than short-time fluctuations. Fig. 54 would be better if the lines around the outside of the drawing had been omitted. In general, lines of this kind around the outside of a chart are likely to be confusing. In this case, the double lines at the bottom of the chart draw too much attention to the bottom and may cause a wrong interpretation of the chart. As charts of this type are usually made so as to have the bottom at zero, the reader of Fig. 54 may get an entirely erroneous idea of the actual increase in the rates of wages. This chart of Fig. 54 should have been drawn with 7/8 inch more room at the bottom so that the scale would begin at zero rather than at $1.00. A glance at the chart as it is shown here might convey to any but a careful reader that the wages of trackmen had more than doubled, within the period of ten years covered by the records thus graphically presented, though the actual wage increase was only from about $1.12 to $1.50. Though Fig. 54 contains a good suggestion for presenting data in popular form, it is in itself misleading because it does not have its base line at zero.

Fig. 55 is a commendable piece of work for popular presentation, as for instance in a magazine. Note the use of dimension marks in two independent horizontal rows so that the upper row indicates the material from which the ships are made while the lower row shows the