Identifier: economiccyclesth00moor (find matches)
Title: Economic cycles: their law and cause
Year: 1914 (1910s)
Authors: Moore, Henry Ludwell
Subjects: Depressions Agriculture -- Economic aspects Supply and demand
Publisher: New York : The Macmillan Company
Contributing Library: University of California Libraries
Digitizing Sponsor: MSN

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, the yield per acre of the crop shows a tendencyeither to increase or to decrease. In order to determinewhether there is a secular change in the yield per acre,for a certain period of time, the yield data are correlatedwith time, and the existence or non-existence of asecular change is inferred from the relative magnitudesof the coefficient of correlation and its probable error.If there be a secular change, the calculation of thecoefficient of correlation of the yield with time is then afirst-step toward the elimination of the secular elementby means of a regression equation in which the co-efficient of correlation is a factor. The method may be illustrated by taking the historyof the yield per acre of corn. In Figure 9 the actualyield per acre in Illinois is plotted for the period 1870-1910. The straight fine showing the secular trend of theyield is the graph of the regression equation betweenthe yield per acre and time. The correlation of the 38 Economic Cycles: Their Law and Cause
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3JOQ j^cf u^ooj.o sf9i^sng Rainfall and the Crops 39 yield per acre and time is r = .382 ± .090, and the regres-sion equation is, ?/= .204x+26.93, where y= yield peracre, a: = time, and the origin is at 1870. The seculartrend is eliminated by means of the facts summarizedin the regression equation: Beginning with the year1870, as many times .204 are subtracted from thejdeld per acre for the several years, as the respectiveyears differ from 1870. For example, the yield for theyear 1872 was 39.8 bushels per acre; consequently thereduced yield for that year was 39.8-2(.204) =39.8-.408 =39.39. Figure 10 traces the yield per acre of cornfreed from the secular trend. Of the four leading crops of Illinois that form thebasis of our investigation, only two, corn and potatoes,show a significant ^ tendency to secular change. Thecorrelation between the yield per acre and time is,for hay, r = .013±.105 and, for oats, r = .043±.105;consequently the figures for the yield per acre of thesetwo crop

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