NATIONAL FOOD CONSUMPTION. 186 



(h) Inedible refuse. 



The effort was made, in the most careful and critical manner 

 possible, to have the final figures for human food consumption rep- 

 resent net values. It is believed that this desideratum has been sub- 

 stantially attained. In the complete report of the study detailed 

 statements regarding the steps taken to get net values vi^ill be given. 



In making up the basic tables each commodity or derivative of a 

 commodity was listed separately and converted as such into nutrient 

 values. In the matter of units of measure the following general 

 plan was followed : In all basic tables the quantities of production, 

 export and import are first given in the American units (bushels, 

 pounds, gallons, etc.) of the original statistics. These quantities 

 were then all converted into metric tons.^ All nutrient values, pro- 

 tein, fat, and carbohydrate are given in metric tons. Energy values 

 are expressed in millions of small calories.* 



Regarding the sources of the basic statistics the following gen- 

 eral statement may be made here.^ For production figures the fun- 

 damental sources, in the case of primary products, are the successive 

 Year Books of the U. S. Department of Agriculture. Each volume 

 of this publication carries as an appendix statistical tables giving 

 the Department's official figures of crop production. A secondary 

 source for crop production figures is found in the successive volumes 

 of the Monthly Crop Report of the U. S. Department of Agricul- 

 ture. Its figures are again official and form the basis of the tabula- 

 tion of the Year Book, but frequently give more detailed informa- 

 tion. Reliable statistics of the derivative products such as flour, 

 meals, etc., are much more difficult to obtain than crop production 

 figures, for the reason that they are not officially collected and pub- 

 lished. In this field resort has been had to a variety of sources, 

 such as trade papers, census returns, special ad hoc inquiries of 

 manufacturers, etc. 



Export and import figures were taken from the official reports 

 (annual and monthly) of the foreign commerce of the United 



3 The metric ton = 2204.6 lbs. 



* A small calory is the amount of heat necessary to raise i gram of water 

 1° Centigrade. 



° This statement is supplemented by more detailed source references in 

 the complete report of the work. 



