IIO DOMESTICATED ANIMALS AND PLANTS 
To avoid large decimals we discard the last figure and take the 
mean at 8.51. From this mean the shortest ear, which was 5 
inches long, deviated 3.51 inches, the next group of four each 
deviated 3.01 inches, or a 
VARIABILITY AS TO LENGTH OF total deviation of 4 x 3.01 = 
Ear — AVERAGE DEVIATION 12,04, Each of the next 
ia Sf pou | y(n any group of six deviated 2.51, 
~ el) ee 3.51 equaling 15.06 in all, and so 
5.5 | 23.01 12.04 on for all the groups. It is 
6.0 6} — 2.51 15.06 manifest that if we continue 
6.5 Bilt eee ys down the distribution in this 
7.0 19 — 1.51 28.09 : ne 
ae || es ee 38-31 way, calculating the deviation 
8.0 37 | = a.51 18.87 for each group, and then add 
8.5 59 | — 0.01 00.59 all together, we shall have the 
Se : oe ns total amount by which a// the 
9- 2:99 39: . 
ios 23 1.49 ai3 ears deviated from the length 
10.5 II 1.99 21.89 of their average, and it is 
11.0 2 2.49 4.98 ‘equally evident that if this 
PO Nes = 299 | — 290 total be divided by the num- 
oes & 240.42 
: ber of ears, we shall have the 
Mean = 8.514 average deviation of these 
24).42 + 286 = 0.872 +, average 
Aeon ears. Such an average is a 
fair measure of variability with 
respect to the character length in this particular variety. The 
Sf( 1.11) 
n 
The process is carried out systematically? in the table above. 
formula would read as follows : = average deviation. 
1 All deviations Je/ow the mean are denoted by the minus sign. In calculat- 
ing deviation by this method these signs are disregarded. In the method to be 
next described these deviations are sgzaved so that the minus signs disappear 
naturally. 
2 In words this formula means: subtract the mean from each of the values 
involved, multiply these differences by their respective frequencies (disre- 
garding the minus signs), add these products, and divide by the total number 
in the frequency distribution. 
3 In all work of this kind systematic arrangement is desirable, not only on 
the score of neatness but of accuracy as well. 
