Page:Graphic methods for presenting facts (1914).djvu/216

 Curves "A", "B" and "C" are shown in Fig. 159 only by way of proving the utility of the pin-board method of keeping costs where there is a large variation in the size of the orders worked upon. The illustration shows these curves superimposed on the pin board only to save space in printing.

In Fig. 160 is shown a chart which may help to make clearer the general principles used in drawing the charts seen in Fig. 157, Fig. 158 and Fig. 159. Fig. 160 shows the appearance of the curves if there are the same number of orders in each class or group and if all classes or groups are of uniform size. It makes no difference in the shape of the curves how many orders there may be if those orders are always uniformly distributed throughout the whole length of the horizontal scale of the chart. It would perhaps have been better if Fig. 160 had been so drawn that the length of the vertical scale would be the same as the length of the horizontal scale. The actual shape of the curve line referring to the percentage of business or the percentage of the total number of pieces would then be free from any possible distortion which it may have received because of the vertical scale being of less total length here than the horizontal scale.

Fig. 160. Chart to Show the Theoretical Shape of Cumulative Curves for the Percentage of Total Orders and the Percentage of Total Business if There Is a Uniform Number of Orders in Each Class or Group

It makes no difference in the shape of the curves, as long as all classes contain the same number of orders, whether there is one order or one thousand orders in each class between vertical lines

The straight line shows the percentage of orders which contain more than any given number of pieces considered on the horizontal scale of the chart

The curved line shows the percentage of the total number of pieces carried by the orders which contain more than any given number of pieces considered on the horizontal scale

If there is not the same number of orders in all groups or zones the curves will take some other shape and the shape will depend on the peculiar distribution of orders as may be seen in Fig. 157, Fig. 158 and Fig. 159

It is especially interesting to compare Fig. 160 with Fig. 159. In Fig. 159 the reader may easily see for himself that there are many more small orders than there are large orders, because the pins are largely concentrated toward the left-hand side of the chart. It is this concentration at the left-hand side which has so greatly affected