20 



H. H. Love axd C. E. Leighty 



From the two cases cited above and bj- an examination of other data 

 contained in Table 4, it seems that correlation may be divided — with only 

 fair accuracy, however — into two classes: (1) those which vary by con- 

 siderable amount from year to year, and which may be known as fluctuating 

 correlations; and (2) those which are fairly constant from year to year, 

 and which msLV be knowm as stable correlations. The distinction between 

 these two c-lasses should be kept in mind in the following pages. 



Correlation of average height of plant with other characters 

 The correlation between average height of plant and total yield of 

 plant (Figs. 1, 2, 3), determined for three years, varies from .512d::.025 



40-45 

 45-50 

 50-55 

 55-60 

 60-65 

 65-70 

 70-75 

 75-80 

 80-85 

 85-90 

 90-95 



JC ■* lO o t^ 



; I I I i 



C^ CO •* LO CD 





1 



























9 



1 

























5 



3 

























1 



6 



4 























/ 



19 



9 











1 













3 



18 



26 



12 



1 



















4 



10 



42 



20 



10 



3 



2 



1 





1 



1 







2 



4 



14 



38 



23 



6 



5 















2 







1 



22 



32 



19 



11 



10 



5 







1 1 







1 





4 



13 



17 



17 



9 



4 



1 



9 















2 



2 



5 



5 



1 





2 



1 





1 



25 62 96 96 81 47 40 31 10 2 5 



Fig. 1. — Average height of -plant in centimeters, subject 

 Total yield of plant in grams, relative. 1909 

 CoefficieJit of correlation = .689 ± .016 



1 



3 



8 



11 



36 



60 



94 



99 



102 



68 



18 



500 



45-50 '11 2 



50-55 16 2 9 



55-60 2 6 7 5 1 21 



60-65 13 9 9 3 34 



65-70 7 46 28 15 1 97 



70-75 13 23 43 32 10 2 123 



75-80 4 13 20 22 27 2 1 89 



80-85 5 3 7 4 3 2 24 



85-90 



90-95 1 1 



3 50 106 109 80 42 7 2 1 400 



Fig. 2. — Average height of plant in centimeters, subject 



Total yield of plant in grams, relative. 1910 

 Coefficient of correlation = .512 ± .025 



