MIGRATION AND BUSINESS CYCLES 
(1898 for imports), 1901 (slight), 1904, 1908 (and 1909, also, for 
clearings), 1914 and 1915, 1919, and 1921 and 1922. 
CHART 7 
InpiceEs oF Economic ConpITIONS, BY FiscAL YEARrs: 1870-1923. 
Ratvo Scale 
Moo 5 
I ey FL 
600 Breas Rocio) Ep en) - eo 
540 C—— =Clearings Index , 500 
400 (Trend=100) -] 200 
Tome PO t= ren million dollars) 
OO ee Daily Production of Pig Iron { 200 
(Unit=thovsand tors) 
2 A 200 
LEARINGS We 
{i = 29 
=k 2 
€0 | 60 
50 50 
40 40 
30 30 
Ze tA 2 
20 / -Q, 1 20 
| fg70-1x 3 1 1860-1685 | 1690-1699 7900-1909 | 1910-1919 — froze] i 
sNumerical data in Tables 13-A and 13-B. 
Pig Iron Production and a Composite Index of Business Cycles. 
Pig iron is basic to many manufacturing industries and to much 
construction work, and, in the form of machinery or other products 
.of iron and steel, is supplementary to practically all industrial ac- 
tivities, hence fluctuations in the production of pig iron ordinarily 
bear a close relation to the volume of industrial activity./ This 
relationship has been frequently noted in previous statistical studies 
of economic conditions. For example, Professor E. E. Day, in his 
construction of an index of manufacturing, compares annual statis- 
tics of pig iron production with his index and finds a striking 
similarity in the fluctuations of the two series.” Because of this 
1Review of Economic Statistics, 1920, p. 367, “The correspondence of pig-iron pro- 
duction with manufacture, when both are adjusted for secular trend, is extraordinary. 
The correlation coefficient is .97.”” (Based upon the period 1899-1919). 
62