42 GENETICS IN RELATION TO AGRICULTURE 
TaBLe V.—To Compute THE STANDARD DEVIATION IN MEAN ToTAL YIELD OF PLANT 
tn Grams (Complete Process Including Calculation of the Mean) 
V f PVs d a | fa 
0.5 3 1.5 -2.958 | 8.750 26. 250 
1.5 50 75.0 —1.958 3.834 191.700 
2.5 106 265.0 —0.958 0.918 97.308 
3.5 109 381.5 0.042 0.002 0.218 
4.5 80 360.0 1.042 1.086 86.880 
5.5 42 231.0 2.042 4.170 175.140 
6.5 z 45.5 3.042 9.254 64.778 
7.5 2 15.0 4.042 16.338 32.676 
8.5 1 8.5 5.042 | 25.422 25.422 
n=400] D(f.V) ="1383 LD(f.d?) = 700.372 
M = 3.458 
te (ge ae 
400 
TasLe VI.—To Compute THE STANDARD DEVIATION BY THE SHORT METHOD 
Let assumed mean = G = 3.5; V—G =d’ 
] 
Vv f | a’ | f.d’ f.dl? | f(d’ +1? 
; | 
0.5 3 3 =o) 27 12 
1.5 50 -2 —100 200 50 
2.5 106 Al —106 —215 106 0 
3.5 109 0 0 0 109 
4.5 80 1 80 80 320 
5.5 42 2 84 168 378 
6.5 7 3 21 63 112 
7.5 2 4 8 32 50 
8.5 1 5 5 198 25 36 
n = 400 esate 701 1067 
—— = — 0.0425) — = 2 
400 er ttiem ea ed 
M=Go+w w? = 0.0018 
= 3.5 + (—0.0425) 1.7525 — 0.0018 = 1.7507 
= 3.458 og = V1.7507 = 1.323 
Check: 2(f) + 2=(f.d’) + 2(f.d’2) = 1067 = S[f(d’ + 1))] 
The short method for computing the standard deviation is based upon 
the same principle as the short method for the mean. The rule, therefore, 
is as follows: Select some number approximating the mean (G); write 
the minus and plus deviation therefrom (d’); multiply each deviation 
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