Graphic Methods for Presenting Facts
It is much easier to see fluctuations if the amount outstanding is plotted in this way from the zero line than if one must gauge the amount outstanding by reading the space between two fluctuating cumulative curves. When data must be read by the length of vertical lines between two curves, the eye is likely to take as the distance between the curves the shortest distance instead of the distance measured on the vertical ruled lines.
In Fig. 136 it was very important to watch the total amount outstanding, for the fund available for loans from the beginning of the loan system until Januar}', 1912, was limited to $200. From January,
CUMULATIVE CURVES
15.5
Cars Shipped
Monthly Daily
2000 10
1 600 9
1600 8
14.00 7
1200 6
1000 5
eoo 4
600 3
400 2
ECO 1
o
^
\
/
N^
[/
\
/
\
Til
^
n
•^11
y
^
fl/
^'"
m ^Ji
/
^
/
/
^
V'
t^
,-•-
"' \
\
N^
'Lf*
^
'^
^
■A
>
^
^
^
y
•>
o
z
o
c
n
^
o
<
^
c
<
Q.
.Average per Day " for Month
Progressive Average per Day
Cumulative Carloads Shipped
Adapted from Factvru
Fig. 135. Carload Shipments from a Manufacturing Plant
Two separate fiscal years are compared on the chart. The right-hand scale shows monthly averages of the number of carloads shipped per day of factory operation. The double-line curves for daily averages and the dotted-line curves for progressive averages are read from the right-hand scale. The heavy solid-line curves are read from the left-hand scale and show cumulatively the total number of carloads shipped since the beginning of each fiscal year