FARM MANAGEMENT PRACTICE OF CHESTER COUNTY, PA. 81 
The fourth column of this table shows that within certain limits 
the work units per man bears a close relation to the size of the farm. 
It is on the farms of 100 acres or less that the small number of pro- 
ductive work units per man is found. For farms larger than this 
there does not appear to be much relation between size of farm and 
productive work units per man. In other words, with the type of 
farming and the general farm methods which prevail here, the farm 
of about 100 acres appears to be the minimum efficient economic unit 
from the standpoint of the proportion of productive work as com- 
_ pared with miscellaneous work. 
FARM ORGANIZATION. 
We have already seen that in the Chester County survey area most 
of the farms are more largely devoted to dairying than to any other 
enterprise. Yet only 157 of the 378 farms conducted by their owners 
had sufficient income from dairy products to be classed as real dairy 
farms. In other words, although this is distinctly a dairy region it 
is by no means exclusively so. There is considerable diversity in the 
local farming. 
DIVERSITY INDEX. 
In order to ascertain to what degree this diversification of enter- 
prises is justified by local experience, it is desirable to have a definite 
means of measuring the degree of diversification on a farm. The 
diversity index furnishes such a means. When the enterprises on a 
farm are all equally important or of equal magnitude the number of 
these enterprises may be used as the measure of diversity. Thus, if a 
farm business is based on three equally important enterprises, its 
degree of diversity is said to be three. But it the enterprises on a 
farm are of unequal magnitude, the degree of diversity may be deter- 
mined as follows: First, find the sum of the magnitudes of all the 
enterprises (in most cases the receipts from an enterprise may be 
taken as 1ts magnitude) ,’ divide the magnitude of each enterprise by 
the sum above mentioned, square each of the quotients, and divide 
_ unity by the sum of these squares. The result is the diversity index. 
In Table XLVII the 378 owner farms are divided into groups based 
on the degree of diversity of their business. Seventy-nine of these 
farms had a degree of diversity less than 3. Their average labor 
income, when adjusted to eliminate the effect of size of farm, was 18 
per cent below the general average. On 107 farms the diversity index 
was from 3 to 3.9. Their labor income was 10 per cent below the 
general average. 
1 The most accurate measure of the magnitude of an enterprise is the total cost of its 
conduct, including interest, depreciation, wages, repairs, materials, etc, 
14138°—Bull, 341—16——6 
