CYCLICAL FLUCTUATIONS IN MIGRATION 139
CHART 27
RELATIVE FLUCTUATIONS IN NUMBER OF IMMIGRANTS AND NON-
IMMIGRANTS, CLASSIFIED, BY SEX: 1905-1924.
Only the relative slope, not |
TOTAL IMMIGRA*™S the vertical position, of these
curves Is significant:
0 a
gd \
IS
\ SCALES OF
PERCENTAGE
FEMALE IMA I57ARTS 20 EANGE
I 160
120
80 Decrease
TOTAL NONIMMIGRA! 75° 40
20 4
3 o
/0
} 20
2 =n 40
Increase | go
60
FEMA..E. NONIMMIGRANT
14151161718 19 [20| 21 [22 | 23]24
Years Ending June 30
sNumerical’data in Table 36.
All of the curves shown in the above chart have been plotted to the same ratio
scale, so that equal vertical distances measured upward indicate the same percentage
increase; and equal distances measured downward, the same percentage decrease, as
shown by the Scales of Percentage Change accompanying the chart. But, to avoid
confusing recrossing, each curve has a different base line; hence in interpreting this
chart only the slope, or vertical change, and not the vertical position of a curve, should
be considered.
Method of Charting.
The method of charting used in Chart 27 may not be familiar to
the reader, and as there are several charts in this and the following
chapter which are similar in principle a few words of explanation
are pertinent. These are so-called “ratio” or ‘rate-of-change”
charts, with a logarithmic vertical scale and also with a different