Page:Walter Renton Ingalls - Wealth and Income of the American People (1924).pdf/50

28 My figures are somewhat lower than those of any other authority, but they differ least from those of Doctor E. E. Day, which perhaps are the most careful and comprehensive of the four with which I have made comparison. The discrepancy among these figures is in itself a ground for suspicion and their lack of harmony with the series that I offer is a warning to us that we must be cautious in using and interpreting index numbers.

However it is not my purpose to enter into a discussion of this subject, which is a side-issue. My own indices, which are computed by a method that unfortunately is impossible until about 10 months after the end of a calendar year are in line with the collateral evidence that I have presented in this chapter to the effect that the physical volume of production increased from 1913 by much less than is commonly computed, and the increase in the national income was far more the consequence of writing up prices than is commonly supposed.

My computations of the total production of commodities in the United States, which are given in detail in an appendix, agree rather closely with the statistics of the Interstate Commerce Commission for the quantity of original freight, which are as follows: