Generating Cycles of Products and Prices 23 



by an illustration. The equation descriptive of the 

 secular trend in the yield of corn was found to be 



y = 103.9 + m^x - .0032.1;^ — .002,233a;3 

 with origin at 1899. The graph of this equation is the 

 smooth cur\'e in the upper part of Figure 4. The 

 equation descriptive of the secular trend of the De- 

 cember farm price of corn was found to be 



y = 102.4+ 1.690a; + .2275x2 - .001,288x3 

 with origin at 1897, the graph of which is also given in 

 Figure 4. The percentage deviations from the secular 

 trend of the actual yield per acre for the separate years 

 from 1880 to 1914 were computed, and these percentage 

 deviations were then correlated with the corresponding 

 percentage deviations of the actual prices from the 

 price secular trend. Table I in the Appendix, which 

 refers to corn, gi\'es an illustration of the computations. 

 Similar calculations were made for the remaining five 

 crops, and the coefficients of correlation between the 

 corresponding percentage deviations, for the years 

 1880-1914, were computed. The resulting coefficients 

 were these : 



Corn r= — .78 



Wheat r = - .23 



Cotton r — — .45 



Hay r= - .68 



Oats 7- = _ .67 



Potatoes r = — .90 



Notwithstanding the fact that the American produc- 

 tion of these crops is only a part of the world supply, 

 there is an inverse relation between the percentage 

 de\'iations of the yield per acre of our crops and the 

 percentage deviations of the corresponding prices. 



