12 
BULLETIN 1277, U. S. DEPARTMENT OF AGRICULTURE 
By substituting any desired values for initial weight of animals, 
length of feeding period, and roughage fed per day. in this equation, 
it is possible to compute the most probable rate of feeding grain 
which would accompany the other conditions, in so far as indicated 
by the data studied, and subject to the limitations of the assumption 
of linear relationships. 8 
Figure 3 shows graphically the rate at which the daily input of 
grain tends to change with changes in each of the three other factors. 
This is drawn to show the relation of changes in the independent 
factors to changes from the average of the dependent factor — grain 
fed per day. 
Including additional data in the analysis would show to what 
extent other factors, such as use of pasture, and quality and breed 
Variations in Man Labor Used on Wheat Prior to Harvest 
3^567 
MAN-HOURS PER ACRE 
Fig. -i. — Data from survey records in Minnesota. Although some farmers: put in as 
much as 8 or 9 hours per acre, four-fifths of the records fell between 3 and 5 hours 
of the cattle, are correlated with the rate of feeding grain. Similar 
analyses should also be made to show the relations of variations in 
input of protein concentrates to variations in the input of other feeds. 
LABOR INPUTS FOB WHEAT 
Variations in labor requirements are more difficult to analyze than 
variations in any other cost element. There is first the difficulty of 
measuring the labor itself, for it varies both by type ( some being 
labor, some woman labor, some proprietor labor, some hired- 
man labor, etc.). and by efficiency within each type: and further, its 
effectiveness is affected by the type of equipment used: that is. 1-row 
or 2-row cultivators, horses, or tractors. In addition, in many cases 
there will not be a smooth, continuous scries. Increases in man-labor 
present additional cultivations or different cultural prac- 
tices. Fur these reasons, each individual study will present its own 
problems of analysis. Frequency tables by different cultural meth- 
md by type- of labor, subsorting, and possibly partial and even 
8 See p. 43 for discussion of linear and curvilinear relations. 
