21,3 Abriol: Death Rates and Economic Factors 319 
crowded dwellings. This, however, probably only means that 
both variables are correlated with other general social factors. 
All of the conclusions in this paper are to be regarded merely 
as suggestive rather than final, until they can be checked by 
further and more-refined statistical analysis. 
ACKNOWLEDGMENT 
Appreciation is hereby extended to Prof. Raymond Pearl and 
to Prof. L. J. Reed for valuable assistance, instruction, and 
personal interest shown throughout this work. 
REFERENCES 
1. Brown, J. W.; GREENWooD, M.; and Woop, F. A study of index 
correlations. Journ. Roy. Stat. Soc. 77 (1914) 317-846. 
2. Census of the Philippine Islands, 1903. U. S. Bureau of Census, 
Washington, D. C. 2, 3, 4 (1905). 
3. EpGewortH, F. Y. On correlated averages. Phil. Mag. London 34 
(1892) 194, cited by Yule. 
4. GALTON, FRANCIS. Family likeness in stature. Proc. Roy. Soc. Lon- 
don 40 (1886) 42, cited by Yule. 
5. Hooker, R. H. Correlation of weather and crops. Journ. Roy. Stat. 
Soe. 70 (1907) 1. 
6. PEARL, RAYMOND. Influenza studies, I. On the general statistical 
aspects of the 1918 epidemic in American cities. Publ. Health Repts. 
34 (1919) 1743-1783. 
7. PEARL, R. The significance of biometry and vital statistics to science 
of medicine. Nelson Loose-Leaf Medicine, New York 2 (1920). 
8. PEARL, R. Influenza studies, II. Further data on the correlation 
of explosiveness of outbreak of the 1918 epidemic. III. On the 
correlation of destructiveness of the 1918 epidemic. IV. On the 
correlation between explosiveness and total destructiveness of the 
epidemic mortality. Publ. Health Repts. 36 (1921) 273-298. 
9, PEARSON, K. Regression, heredity, and panmixia, Phil. Trans, Roy. 
Soc., London Ser. A, 187 (1896) 253, cited by Yule. ° 
10. West, C. J. Introduction to Mathematical Statistics. Columbus, R. 
G. Adams and Company (1918). 
11. Yuue, G. U. On the theory of correlation. Journ. Roy. Stat. Soc. 60 
(1897) 812. ; ; 
12. YuLE, G. U. On the interpretation of correlations between indices or 
ratios. Journ. Roy. Stat. Soc. 73 (1910) 644, 
