Generating Cycles of Products and Prices 27 



ACTUAL Index NUMMRS OF Prico ■ 

 FoREOkST iNO£x NuMWRsor Prices 



GENERATiNa Cycles of yield per acre 

 Derived Cycles or Prices 



Figure 8 

 Upper part : Actual index numbera of prices of the six representative crops and 

 the index numbers of prices forecast from the index numbers of 

 the yield per acre by means of the formula 

 2/ = — 1.295x — .02. 

 Lower part: Generating cycles of the yield per acre of the crops, 

 y =1.6 + 20.0 sin (45°< + 109°), origin at 1882; 

 Derived cycles of prices of the crops computed from the generating 

 cycles of jneld by means of the formula, 

 y = - 1.2951 — .02. 



of the combined yield and the index of the combined 

 prices. 



The coefficient of correlation between these two 

 variables is r = — .69, and the equation expressing 

 their relation is 



y = —1.295a: -.02 



