108 Negro Migration 



increasing rapidly by migration the relationship is clearer 

 still. There is no way for population movement alone to 

 increase the number of independent farmers unless oppor- 

 tunity previously exists for them. In fact, when planters 

 desire to hold to the labor or share tenant system, an influx of 

 Negroes aids them because it increases the available labor 

 supply. 



If, therefore, it can be established that increase in inde- 

 pendent Negro farmers is more closely associated with in- 

 crease in population than is increase in Negro farm labor, 

 then we will have shown that the lack of agricultural oppor- 

 tunity leads to movement from a district while favorable 

 opportunity for farmers leads to movement into a district or 

 to such a condition that young men find places on farms as 

 they grow up and the county does not lose them. 



To establish this point a quantitative statement of the 

 relationship is desirable. This can be arrived at only by em- 

 ploying a logical and exact method of measuring the relation- 

 ship between such factors which vary in a number of cases. 2 



The following table is constructed so as to make these 

 variations in Negro population and farm increase stand out 

 for the counties in Georgia. 



In order that the comparisons might be accurate, all coun- 

 ties were eliminated from consideration in which very small 

 Negro rural population, or suburban populations rendered 



2 The method of correlation is presented in as popular a form 

 as possible. Sufficient use has been made of it in measuring 

 relationships in economics and biology to warrant the omission 

 of the detailed mathematical proof of the assumptions under- 

 lying it. These are given fully by G. U. Yule in "An Introduc- 

 tion to the Theory of Statistics," and by H. L. Moore, in 

 "Forecasting the Yield and Price of Cotton." The principal 

 steps in the reasoning and abridged proof of the derivation of 

 the Pearsonian co-efficient of correlation are given in the sta- 

 tistical appendix. 



