Page:Graphic methods for presenting facts (1914).djvu/285

 for the last month of the preceding fiscal year instead of using a dot as shown in Fig. 204.

Fig. 208. Sales of the "X.Y.Z." Automobile Plant for Three Consecutive Years

These are the same cards that are arranged vertically in Fig. 207. The horizontal arrangement permits seeing the figures for each month, quarter, or year, but does not show the changes in curve shape from year to year as well as does the vertical arrangement. The person handling the cards has his choice of the vertical or the horizontal arrangement for the cards

The separate cards for different years, which in Fig. 207 are arranged vertically one above the other, may be laid horizontally as in Fig. 208. Here the cards are superposed on a black background, the left-hand and middle cards each overlying the card to the right, so that the curve appears continuous. The vertical arrangement allows of a very accurate analysis of changes which have occurred from month to month of each year. With the horizontal arrangement it is not so easy to compare any month of one year with the corresponding month of another year, but it is easier to see the changes which have occurred in a curve as a whole throughout a period of years. Thus in Fig. 208 it is much easier than in Fig. 207 to see that sales dropped seriously in the first half of 1911, and that they increased far beyond any previous record during the last half of 1911. The vertical arrangement is useful for one purpose: the hori