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 Fig. 137 shows in detail for the same loan department the operations which are summarized in Fig. 136. In Fig. 137 the heavy line shows the actual amount of money loaned each month, while the dotted line shows the amount of money paid back each month. The data for these two curves were later added month by month on a cumulative basis and plotted into the two curves, "Loaned" and "Paid-back," in Fig. 136. Because of the great fluctuation in the amount loaned and paid back each month, the operation of the department as a whole can be seen much more easily from the cumulative curves of Fig. 136 than from the actual monthly-loan curves of Fig. 137. In general, the cumulative curve is of very great assistance in showing phenomena in which there are violent fluctuations such as are seen in the loan curve in Fig. 137.

Fig. 136. Total Loans Made to Employees by a Large Industrial Corporation and Total Amount Paid Back, Shown Monthly Since the Beginning of Loans

The two upper curves are plotted on a cumulative basis. The bottom curve shows the amount outstanding and is equivalent to the vertical distance between points on the two upper curves. The capital devoted to loans is indicated, and the chart permits easy reading of the amount of capital not on loan at the end of any month

It is interesting to note in Fig. 137 that the peaks and valleys in the curve showing the amount paid back follow ordinarily one or two months behind the peaks and valleys in the curve showing the