i834 



RURAI, ECONOMICS 



Table VIT. — Mammal trials loitJi nitrate of soda ; probable error of results. 



Totals 

 Means 



Unmanured plots 



Production 



20.1 

 20.3 

 18.7 

 18.9 



78.0 

 19.5 



Deviation from the mean 



Simple 



+ 0.6 

 + 0.8 



— 0.8 



— 0.6 



Squared 



0.36 

 0.64 

 0.64 

 0.36 



2.00 

 0.50 



Manured plots 



Production 



Deviation from the mean 



Simple 



Squared 



26.2 

 26.9 



23-3 

 27,1 



103.5 



25.86 



+ 0.3 



+ i.o 



— 2.6 



+ 1.2 



0.09 

 1. 00 

 6.76 

 1.44 



9.29 

 2.32 



Ed 



0.48 



2X2 , 2 X 9.29 _ 0.66 



4X3 4X3 



2) The best size for experimental plots. In this connection the results 

 of I/ARSEN in Sweden may be cited : 



Size of plot Probable error 



1/16 are (i) 16.7 per cent of the mean 



1/8 " 10.7 



i/t " 0-8 



1/2 " 8.5 



I " 7-7 



(i) I are = 0.025 acres. 



